Slalom Water Skiing; Sport-Specific Conditioning; Prehabilitation; Tandem Stance; Balance

Keywords: slalom water skiing; sport-specific conditioning; prehabilitation; tandem stance; balance

Physiological Considerations and Specific

Conditioning Nicole M.Mullins,PhD,CSCS Youngstown State University,Youngstown,Ohio Slalom water ski courses comprise 6 fixed run in match-play format, in which one buoys, 3 positioned 11.5 m (37.7 ft) to the skier must simply outperform another in s u m m a r y right of a centerline and 3 to the left (see head-to-head fashion. This article discusses the unique Figure 1) (41). Two additional rows of biomechanical and metabolic buoys, 2.1 m (6.9 ft) apart, sandwich the Rope lengths range from 18.3 m (60 ft) for demands of slalom water skiing, as centerline and delineate the path through novices to almost half that for world-class well as important considerations which the boat must travel. Skiers enter skiers. The current world records for men for sport-specific training and the course through a pair of buoys and women have been set at rope lengths prehabilitation. constituting the entrance gate, maneuver of 9.75 m (32 ft) and 10.25 m (33.6 ft), their skis around the outsides of all 6 turn respectively (40). Note that merely to buoys, and exit the course through a final reach the turn buoys using these rope Introduction pair of exit buoys. In competition, athletes lengths, the body must be almost ski in rotation and, if they complete a completely extended and that shorter To the spectator, elite-level slalom water successful pass, advance to successive individuals may never be able to beat these skiing may look like an effortless aquatic rounds. With each new round, the records, regardless of skill. joyride. For the skier, however, a towrope is shortened, increasing the successful pass through a slalom course difficulty of rounding the buoys. As rope To add still more to the challenge, boat requires an intricate blend of technique, lengths shorten, both the skiers’ paths speeds increase with skier ability, ranging timing, strength, muscular coordination, behind the boat and their lean toward the from 26–28 mph (42–45 kph) for and dynamic balance. This article will water’s surface must become more novices, to 34–36 mph (55–58 kph) for review the unique biomechanical and angular, intensifying the challenges to experts, with skiers actually accelerating physiological demands of slalom water balance and stability (see Figure 2). The to even faster speeds. At 36 mph (58 skiing and will make several winner is the skier who successfully kph), a calibrated ski boat takes 16 recommendations for injury prevention negotiates the most buoys in the final seconds to travel straight through a and sport-specific training. round. Occasionally, competitions may be regulation slalom course from entrance

42 August 2007 • Strength and Conditioning Journal weather conditions, athletes living in boat maintenance. Although certain regions with cold seasons are at a distinct environmental conditions, such as disadvantage compared with those living extreme cold, high winds, heavy rain, and individual ski time to about 15 minutes in areas with warm weather yearround. electrical storms, impose obvious every 2 hours. Cold climates not only limit technique limitations on ski training (e.g., choppy development to a few months per year, water increases the difficulty of both For all of these reasons, it is virtually but also generate little overall support for skiing and boat driving), even mild winds impossible for many slalom water skiers to the sport via ski enthusiasts, courses, and light boat traffic can thwart ski themselves into peak condition, thus competitions, and boat dealerships and possibilities of peak performance. For this repair facilities. In addition, short ski reason, many elite skiers train on private making supplemental conditioning seasons may contribute to increased risks ski lakes, devoid of recreational boat programs imperative. Program goals of injury by pressuring athletes to sidestep traffic and landscaped to somewhat shield should center on developing and sound skill and conditioning progressions the wind. Others, however, must train on maintaining the neuromuscular in efforts to make up for lost time. public waters and either contend with characteristics consistent with sound rough conditions or limit skiing to times slalom technique, prehabilitating the Other barriers to accumulating quality ski when calm is more likely to prevail (usually muscles and joints most vulnerable to time involve the day-to-day variability of early morning or twilight). injury, and correcting any musculoskeletal weather and recreational boat traffic, the imbalances that stem from chronic ski number of skiers training on a given Most skiers, whether on public or private training. course, and the expense of ski waters, must share access to a slalom course, which can profoundly impact Biomechanical,Metabolic, and to exit gates. Within this time, skiers skiing is to slalom water ski. However, Injury Analyses must cover at least an additional 35 m for several reasons, it is difficult for many All sport-specific conditioning programs (~115 ft) on a zigzag path, which to accumulate enough on-the-water should be based on thorough requires alternately decelerating to 20–22 training to realize their skiing potential. biomechanical, metabolic, and injury mph (32–35 kph) to round the buoys and Most important, because quality ski analyses of the athletic event. Core accelerating to as fast as 70–80 mph individual ski time. In efforts to promote considerations for optimizing program (113–129 kph) (76) through the equitable ski time, courses generally have design include the primary muscle groups, straightaways. policies governing skier turn length and types of muscle actions, joint ranges of rotation motion, movement speeds, and energy (e.g., 1 system contributions required in the event, turn = as well as common injury sites and 6 mechanisms. These features, however, are passes, more difficult to characterize for some events than for others, particularly for those that have been the subject of little scientific research, such as slalom water skiing.

Biomechanical Analysis Biomechanically, slalom water skiing can be broken into the deep-water start and several repeating movements for skiing to Figure 2. Increased angulation needed at shorter rope lengths.Blue:boat;orange: and around each of the 6 turn buoys. The skier buoys;____:rope;----- :skier. repeating movements of slalom skiing Figure 1. Major slalom course dimensions.Red:entrance and exit gates;yellow:boat 3 falls, guides;orange:skier buoys; ← and → : skier path. have been described previously by or 15 Eberhardt (20) and Leggett et al. (47) but training depends on amenable water and equipment, course memberships, and will be reviewed and expanded upon for Rationale for Supplemental minutes, whichever comes first). the purposes of this article. For the Training Equitable, however, may be far from It stands to reason that the best way to optimal. For example, sharing a course develop expert skills in slalom water with 8 others on a given day would limit two-footed, deepwater start, both feet are bindings, with the dominant foot forward. secured in tandem (heel to toe) in the ski The skier assumes a crouched position in

August 2007 • Strength and Conditioning Journal 43 the water, with the front knee very near the position, with eyes focused on the target length, and boat speed. It results partly chest, the ski angled approximately 45° away from vertical, and the ski tip protruding approximately 10–12 in. above the surface. The arms are extended, the handle held with a closed, alternated grip, and the rope positioned to the side of the ski opposite the front foot. As the boat begins to pull, the skier applies firm pressure to the ski with both feet, keeping the knees bent and shoulders back. Intense static action and dynamic balance are needed to prevent being pulled outside the very narrow, unstable base of support (BOS) while emerging to stand.

After emerging from the water, the skier travels to the far left of the boat wake to prepare for rightward acceleration through the entrance gate toward the first turn buoy. To initiate acceleration, the skier Figure 3. The lean. must forcefully pull the towrope handle buoy. The scapulae should be retracted, from conscious actions and partly from a toward the left hip, by retracting the arms fairly extended, and handle pressed natural pendulum effect of the rope scapulae, extending the shoulders, and first close to the body. The lumbar spine and pulling from the opposite direction (left). flexing, then extending the elbows to hips should be extended as much as Conscious actions include standing slightly position the arms close by the sides. This possible, with the knees and ankle flexed, more erect and shifting the COM leftward movement requires forceful actions by the so that the entire body leans away from the by applying pressure to the handle, still finger flexors to grip the handle; by the boat (Figure 3). Ankle position will vary held close to the hips. biceps and triceps brachii to flex and according to the type of ski bindings used, extend the elbows; by the trapezius, individual flexibility, and changes in the rhomboids, pectoralis minor, and rotator angles of the hip and knee joints. The skier cuff musculature to retract, depress, and should strive to maintain this leveraged stabilize the scapulae; and by the latissimus body position throughout much of the dorsi, posterior deltoid, pectoralis major course, requiring strong actions by the (sternal head), teres major, and triceps erector spinae to extend the back, by the (long head) to extend the shoulder joint. gluteus maximus and hamstrings to extend Directing the handle toward the left hip the hips, and by virtually all lower causes counterrotation, or turning of the extremity musculature to appropriately shoulders and hips toward the right. manage the many forces acting on the Counterrotation is critical to helping the body (e.g., drag, lift, buoyancy, tension, skier shift the center of mass (COM) and gravity). put the ski on its right edge. A ski “on edge” cuts through the wake faster and After pulling, accelerating, and leaning with less bounce than a “flat” ski. away from the boat, the skier must cross the wake, change edges of the ski (from At the same time the skier initiates right to left), decelerate, and arc around the acceleration by pulling on the rope, the first turn buoy. Edge change should occur rest of the body must be positioned for somewhere between the center of the maximum leverage against the boat. The wake and shortly after crossing it, head should be held in the neutral depending on skier ability and style, rope

August 2007 • Strength and Conditioning Journal 44 After a successful edge change, the skier into flexion, slack will appear in the rope introduce slack into the rope. The must precisely time the “reach” to and greatly reduce the likelihood of a subsequent uptake of that slack by the initiate a tight turn around the outside of successful pass. The forces exacted when boat can result in a powerful, whip-like the buoy. Turning too early will result in slack lines pull taut can cause horrendous application of force to the skier. If this missing the buoy on the inside, whereas “out the front” crashes that greatly force (or the anticipation of it) does not turning too late will allow travel too far endanger ankle, knee, back, neck, and completely fell the skier, it will at least down course to make the next buoy. To shoulder joints. Even when falls are likely cause some degree of shoulder girdle initiate the reach, the skier releases the avoided, they still can impose enough protraction, spine, hip, and shoulder right (outside) hand and then extends the stress to cause injury. flexion, and, depending on the skier’s handle with the left smoothly toward the reaction, either knee extension or boat so as to maintain rope tension Finally, at the apex of the turn, the skier increased knee flexion. Accordingly, (Figure 4). This requires eccentric action must regrasp the handle with the free strong eccentric action by the muscles that by the shoulder extensors and strong hand and once again pull forcefully counter these movements will be needed fixation by the scapular stabilizers. The toward the outside hip (right). This again to resist the force and prevent falling. The free arm should be controlled close to initiates counterrotation and on-edge trapezius and rhomboids will be called the waist, because allowing it to fly high acceleration toward the next buoy, on the upon to resist scapular protraction; the in the air or behind the body could left side of the course. The skier who can rotator cuff musculature to resist contribute to loss of balance. If proper complete this complex sequence 5 more glenohumeral distraction; the latissimus body positions are maintained, the reach times within 12–14 seconds can claim a dorsi, teres major, posterior deltoid, and triceps brachii (long head) to resist shoulder flexion; the erector spinae to resist spinal flexion, the gluteus maximus and hamstrings to resist hip flexion; and either the hamstrings or the quadriceps to resist knee extension or flexion, respectively. The importance of such eccentric action to slalom skiing is evidenced by the superior knee extensor strength of professional water skiers (46).

No biomechanical analysis of a sport carried out entirely on such a narrow BOS as a slalom water ski (approximately 15–20 cm wide) would be complete without some discussion of balance, stability, and postural control. In general, “postural control” refers to the body’s ability to attain, maintain, and restore balance Figure 4. The reach. during activity (66), especially upon further shifts the COM to the left, successful pass. exposure to forces that threaten it, causing considerable lateral body lean Because balance and joint positioning are including muscular action, gravity, friction, and redirection of the ski in the opposite challenged constantly by changing water and ground reaction (63). “Balance,” in direction. During the sideward lean, the conditions, driver performance, and turn, is recognized as the state present quadratus lumborum is strongly repercussions of imperfect technique, a when all forces acting on a body are equal activated, as indicated by the research of great deal of muscle coactivation and some and oppositely directed (6), such that the McGill et al. (55). If proper body degree of each type of muscle action— body remains either at rest or at constant positions are not maintained, any concentric, eccentric, and static—are velocity. “Stability” refers to the ability to number of muscles and joints may be needed to assume, to hold, and to resume resist balance disruption and depends called upon to restore balance or to proper body positioning. For example, a importantly on a body’s BOS and COM, protect against damage during falls. For skier who pulls too forcefully on the as well as friction or drag forces (34). In example, if the trunk is pulled forward handle may overaccelerate and will general, heavier bodies, with lower COMs

August 2007 • Strength and Conditioning Journal 45 and large BOSs, encountering high friction contributions by the stepping and grasping Metabolic Analysis or drag forces, have greater stability. Thus, strategies are precluded by the fixed foot Metabolically, slalom water skiing is tall, lean slalom skiers performing on position and the need to maintain firm somewhat difficult to characterize. A smooth, narrow skis are presented with rope tension. Thus, the hip strategy must cursory assessment of the high-intensity extraordinary stability challenges, even bear the major responsibility for muscular efforts, rapid accelerations, and before encountering wind-, wave-, and maintaining balance. To enhance its short duration of a single slalom pass boat-imposed forces. effectiveness, skiers should regularly might suggest its classification as a pure perform some conditioning exercises power sport. However, closer inspection The mechanisms underlying postural using a tandem stance, as on their skis, and reveals that some of its movements are control during balance perturbations are should strive to minimize stepping and explosive (e.g., pull and backward lean just extremely complex and arise from the grasping movements. As stance width prior to wake crossing), whereas some are collective functioning of the decreases, body movements more easily relatively static (e.g., knee flexion and back somatosensory, visual, and vestibular shift the COM outside the BOS and extension). Moreover, its intensity, systems (4, 66). These systems all provide increase postural sway (45, 93). Increased duration, and considerable static activity sensory input regarding body position to sway, in turn, intensifies stabilizing (during which muscle blood flow is the central nervous system, which then mechanisms, including muscle and joint restricted) make it heavily reliant on the integrates it and activates an appropriate proprioception. Therefore, purposefully phosphagens (ATP-PCr) and anaerobic motor response. Motor responses to narrowing the stance during conditioning glycolysis for energy, yet it also appears, postural disturbances are generally exercises can specifically help train better for several reasons, to depend significantly classified as “fixed-support” or “change- balance. on aerobic metabolism. First, in high- insupport” strategies (66), depending on intensity running events of similar whether or not the BOS is altered. The Many exercises, such as squats, can be duration to a single slalom pass (e.g., 200- major fixed-support responses are the modified to incorporate the tandem stance m sprint), aerobic contributions have been ankle strategy and the hip strategy, which and thereby more specifically impose the reported to be as high as 28–33% (19, 78). involve activating ankle and hip joint demands of slalom water skiing. Several Second, many skiers train multiple passes musculature, respectively, to reposition authors (10, 39, 43) already have consecutively, imposing continuous work the COM over the BOS (13, 63). The ankle recognized the value of performing squats for 3–4 minutes and extending into the strategy dominates in correcting minor and other conditioning exercises with a aerobic realm of the energy continuum. postural disturbances, whereas the hip split stance to enhance training specificity. Third, the sheer proportion of muscle strategy takes over when postural Because many athletes perform skills using mass recruited during slalom skiing may disturbances are more severe, when ankle a staggered, rather than a parallel, stance activate central cardiovascular command motion is limited, or when unstable (e.g., running, jumping, throwing), it mechanisms and thereby raise aerobic surfaces reduce the effectiveness of the makes sense for their training to energy contributions. Cardiorespiratory ankle strategy. Change-in-support incorporate this position. Likewise, responses to exercise are regulated by strategies include stepping in the direction because slalom skiers perform exclusively anumber of factors, including peripheral of the displaced COM to move the BOS in the tandem position, their conditioning reflex activity within the working muscles under it and making grasping movements should reflect this unique motor demand. (57, 70) and central command (30, 71). with the limbs to offset destabilizing shifts The tandem squat also may benefit slalom Though the mechanisms underlying these in the COM (13, 52, 63, 66). When these skiers through its nature as a closed-chain responses are beyond the scope of this strategies fail to correct balance, falls exercise. Closedchain exercises are known paper, response strength is related directly occur. to impose less joint shear stress and to to active muscle mass and exercise stimulate greater motor unit activation, intensity (24, 92). In simple terms, the The value of understanding the major muscle cocontraction, joint congruency, more muscle involved in an activity and postural control mechanisms lies in and proprioception than do open-chain the higher the intensity at which it works, providing insight into the importance of exercises (47, 48, 85, 90)—factors all the greater the stimulation of heart rate, the hip and trunk musculature to conducive to enhancing postural control blood pressure, myocardial contractility, stabilizing posture in slalom water skiers. and reducing risks of injury (18, 38, 49, 57, and cardiac output. In summary, though a Contributions by the ankle strategy are 77). high aerobic capacity is not necessary to limited by the unstable sport surface and excel at slalom water skiing, neither is pure modern, high-wrap bindings that now explosive power. dominate the slalom ski industry, and

August 2007 • Strength and Conditioning Journal 46 Additional support for significant age aerobic capacities (11). Other groups Injury Analysis aerobic contributions to slalom water also have shown Alpine slalom skiers to Unfortunately, there is little skiing is provided by investigations of its have above-average aerobic power (14, documentation of the common sites, Alpine counterpart. Though there are 72, 83), high proportions of slow-twitch incidences, and mechanisms of injury obvious, fundamental differences muscle fibers (72, 89), and selective among skilled slalom water skiers. between downhill slalom skiing and reduction in muscle glycogen from type I Several reports identify a vast array of slalom water skiing, there are also clear versus type II fibers following ski injuries sustained during water skiing, similarities in both technique and athlete training (84, 89). ranging from minor strains to profiles. Movement patterns in both catastrophic propeller injuries (5, 32, 33, types of slalom skiing involve similar At present, no studies have directly 36, 37, 64, 68, 75, 80). However, these body inclination, counterrotation, edge measured the energy demands of slalom reports neither adequately distinguish changing, and speed, and athletes in both water skiing. Two have reported trends among the sport’s different disciplines tend to be tall, lean, strong in moderate-to-high levels of both subdisciplines (slalom, trick, jumping, the same muscle groups, and possessing anaerobic and aerobic power among elite and barefooting) nor delineate of moderately high aerobic capacities (1, water skiers (46, 47), but, as cross- contributions from fatigue, equipment, 46, 47, 54, 60). Several reports on Alpine sectional studies, cannot distinguish driver skill, or other miscellaneous skiing recognize the dominance of whether sport-specific training or natural factors (e.g., alcohol or drug use by skiers anaerobic metabolism but also the selection explain the characteristics. With or drivers, interference from birds, fish, significance of aerobic metabolism. continuing advancements in portable or submerged objects). Moreover, they Veicsteinas et al. (87) reported the metabolic systems, direct measurements draw different conclusions as to the anaerobic:aerobic energy contributions of oxygen consumption during water frequency and severity of injuries among to Alpine slalom skiing to be skiing may soon be feasible. Until then, skilled versus novice skiers. Skilled skiers’ approximately 60%:40%. White and indirect insights into the sport’s risks likely are reduced by experience, Johnson (90) found that anaerobic metabolic requirements seem to indicate better ski conditions, and greater fitness exercise tests were better than aerobic that elite performance is not limited to but are increased by faster skiing speeds tests at predicting performance in either the genetically elite anaerobic or and more highly competitive situations. competitive skiers, but that skiers aerobic athlete. Future research should seek to clarify nevertheless had above-aver- these ambiguities. Table 1 Water skiing Injurie s

Sites of injury % Lower extremity injury sites % Types of injury %

Lower extremity 34.0 Knee 30.8 Strain or sprain 36.3

Trunk 27.1 Thigh 25.7 Contusion or abrasion 17.1

Face 20.8 Foot 14.7 Laceration 17.1

Upper extremity 13.0 Lower leg 13.9 Fracture 9.0

Head 4.3 Ankle 13.4 Traumatic brain injury 2.4

Other 0.9 Toe 1.5 Other 18.5

Data are from Hostetler et al. (36).

August 2007 • Strength and Conditioning Journal 47 The best characterization of water skiing quadriceps, slalom skiing constantly loads instead of assuming a wide, parallel stance, injuries to date is the report of Hostetler et the back extensors and forearm flexors stand with the feet in tandem. It may be al. (36), which describes water skiing (n = and may warrant compensatory training of helpful to place the feet on a line on the 517) and wakeboarding (n = 95) injuries the abdominal, chest, and forearm floor or a seam in sustained in the United States between extensor muscles. This recommendation is January 1, 2001, and December 31, 2003. supported by data showing professional Data extracted from the National water skiers to have significantly stronger Electronic Injury Surveillance System upper back musculature than untrained show that among skiers, both the types controls have, but similar chest strength, and sites of injuries were distributed suggesting training-induced muscular broadly, as shown in Table 1. The lower imbalances (46). extremity was the most commonly injured body region (34% of all injuries), whereas Another study of potential relevance to sprain or strain was the most common injury prevention is that of Keverline et al. diagnosis (36.3% of all injuries). Within the (44). This group measured force lower extremity, specific injury sites were transmission through the upper body distributed widely, though injuries to the during the deepwater slalom start, as a knee and thigh accounted for more than means of estimating stress levels half of all injuries to this region (56.5%). chronically imposed on skiers’ arms and shoulders. A load cell incorporated into a Consistent with the findings of towrope assembly showed a mean relative Hostetler et al. (36) is the high prevalence force of 2.0 ± 0.5 times body weight as of acute hamstring trauma among skiers were pulled from partial submersion published case reports of water skiing to stable planing on the water. The authors injuries (12, 15, 51, 75, 88). Hamstring concluded that such high forces could strains, ruptures, and avulsions seem to contribute to, or exacerbate, existing upper Figure 5. The tandem squat. afflict both novice and skilled skiers, extremity pathology—a conclusion generally as a result of a forward fall in supported by anecdotal reports from the matting. Slowly flex the knees, hips, which the knees extend and hips hyperflex. skiers with chronic shoulder problems. and ankles to descend in a controlled Preexisting pathology and weakness have fashion, while simultaneously squeezing Analysis of the published data, not been deemed contributing factors, and the knees together. Concentrate on biomechanical requirements, and thus these injuries may not be preventable. minimizing sway. Strive to descend until anecdotal information from athletes Nevertheless, skiers’ the rear thigh is parallel to the floor, while suggest that the lower extremity, back, and hamstrings:quadriceps strength ratios keeping the body weight evenly distributed shoulders are the body regions most should be assessed to ensure that they between the feet, the feet flat on the floor, susceptible to injury during slalom water meet minimum recommendations. and the knees from moving beyond the skiing. However, because the Optimum ratios are thought to vary for toes. Return to the fully upright starting unpredictable nature of falls makes it different types and speeds of athletic position and repeat for the desired number possible to injure any area, sound movements, but a ratio of at least 0.5 has of repetitions. Although skiers do not prehabilitation programs will address all been recommended to reduce risks of alternate foot position on the ski, this major muscle groups, as well as individual hamstring injury (25). Because slalom exercise should be trained with both the weaknesses and imbalances. skiing constantly loads the quadriceps, right and left leg leading to promote skiers may need to place greater emphasis balanced strength and proprioceptive on hamstring strengthening to achieve and Sport-Specific Exercises function. maintain better proportionality. Tandem Squat (Figure 5) To perform the tandem squat, position the Athletes first should attempt this squat Disproportionate training also may be body, with dumbbells or a barbell, as for a modification without added resistance. warranted for other muscle groups to basic back squat (dumbbells at the sides or Once a target number of repetitions can be prevent the development of muscular barbell resting on the upper back, chin up, performed with minimal sway and without imbalances that could predispose to injury, eyes focused straight ahead or slightly stepping, progression may be made to especially during the ski season. As for the upward, shoulders retracted). However,

August 2007 • Strength and Conditioning Journal 48 squatting with dumbbells or a barbell. As small amount may be acceptable and is lower back flat or slightly arched, hands an intermediate step to develop likely to occur at times during slalom directly below the shoulders, knees confidence in the technique, individuals skiing. slightly bent) but place one foot directly may perform the exercise using a Smith in front of the other. Keeping the machine. However, because Smith Tandem Deadlifts (Figure 6) The stiff- dumbbells or barbell very close to the machines essentially remove the legged deadlift—excellent for legs throughout the movement, slowly proprioceptive challenge of the exercise, strengthening the entire posterior flex the hips until the hands approach the progression to free weights should be chain—is another exercise well suited to tops of the shoes, the movement is made as soon as possible. The dumbbell incorporating the balance challenge of limited by hamstring tension, or the back squat is recommended as the primary the tandem stance. It is particularly begins to round (27, 65). Slowly reverse

Figure 6. The tandem deadlift. Figure 7. The supine plank. version, because dumbbells exert valuable for training the ability to recover the movement to stand fully erect, then independent forces on the upper limbs, from being pulled forward while skiing. repeat. just as the towrope does at times during However, it is a high-risk exercise, due to slalom skiing. the length of the lever arm between the Supine Plank (Figure 7) The supine resistive force and joint axis of rotation plank exercise is adapted from the supine Some athletes may find it difficult to (27, 65). The long lever places the back plank test used in diagnosing high keep the knees, particularly the rear knee, muscles at a mechanical disadvantage hamstring tendinopathy (25). When from moving slightly beyond the toes and requires them to produce forces included in a comprehensive training when performing this exercise—a greater than the loads actually being program, this exercise may help improve common contraindication because of its lifted. Only athletes free from hip and muscular strength, endurance, association with high shear forces at the spine pathology, cognizant of proper proprioception, and injury resistance knee joint (3). Though increased technique, and possessing of adequate throughout the entire posterior chain. To shearing is clearly undesirable and strength and flexibility in the hamstring perform the supine plank, lie supine, with individual flexibility deficits should be and lumbar regions should attempt this the elbows directly under the shoulders addressed, some evidence suggests that exercise. and forearms on the ground, parallel to restricting forward movement of the the torso. Lift one foot and place it in knees while squatting may simply To perform tandem deadlifts, position tandem above the other. Raise the pelvis increase force application to the hips and the body, with dumbbells or a barbell, as so that the body weight is supported back (26), thereby raising the injury for the traditional stiff-legged deadlifts entirely by the forearms and single heel. potential. Thus, forward movement of (chin up, eyes focused straight ahead or Hold for 5–10 seconds, then switch feet, the knees should be minimized, but a slightly upward, shoulders retracted, without lowering the pelvis. Take care to

August 2007 • Strength and Conditioning Journal 49 avoid breathholding during the exercise. To perform the prone plank, lie face to 90°. The iliac crests should be aligned Complete sets of 10–20 alternating down, with the head and chest propped up vertically and the knees also flexed to 90°. repetitions (5–10 repetitions per leg). by the forearms. Lift one foot and place it Viewed from above, the body should form Sets also may be completed by in a tandem position above the other. a straight line from head to knee. Raise the performing 5–10 consecutive repetitions Raise the body off the ground to fully hips off the ground to form a straight body on a single leg, by raising the pelvis, support it on the forearms and ball of one line when viewed from the front, hold the holding for the desired count, lowering foot, maintaining a straight body line from position for several seconds, then lower momentarily to the rest position, and head to foot. Hold the position for several under control to the rest position. Over repeating. seconds, then lower under control to the time, increase the duration of the hold, rest position. Avoid breath-holding during remembering to breathe normally Despite its simple appearance, the supine the exercise and perform 2–3 sets, throughout. Perform 2–3 sets, alternating plank is an intense exercise and it is alternating support legs. Progression for sides. important that a proper warm-up precede this exercise should entail increasing it. It is recommended that its progression duration of the hold. To perform the intermediate version, entail increasing repetition duration position the body as for the basic side and/or number, rather than loading the Side Bridge bridge but extend the knees and move the torso with additional weight. Current According to McGill (56), the isometric top foot into a tandem position in front of the other. To perform the advanced version, position the lower body as for the intermediate version but use the hand, rather than the forearm, to support the upper body (Figure 8). Once the advanced side bridge can be performed with minimal sway for the desired amount of time, athletes can practice alternately rolling from support on one hand to support on the other, reestablishing stability as quickly as possible (rolling side bridge) (56). This enhances the ability to steady the body after repositioning the COM, as is necessary during ski edge changing. Torso Rotations Various cable, resistance band, and medicine ball exercises that strengthen the torso with a rotational element may benefit water skiers by increasing power during Figure 8. The advanced side bridge. the slalom pull and counterrotation. research indicates that muscular endurance side bridge is an effective exercise for Several cable “chop” exercises have been of the trunk extensors bears a much training the quadratus lumborum and recommended previously for enhancing stronger relationship with back health than abdominal obliques. Because these multiplanar, functional strength for other with muscular strength (56). muscles are important to the reach phase sports (16, 22, 23) and are well suited to of the slalom turn, this exercise is an skiers. To perform oblique cable chops, Prone plank excellent addition to the water skier’s stand facing away from a cable system, at The prone plank is essentially the mirror training program. It can be performed in an approximate 45° degree angle, with the image of the supine plank, performed several progressions, from basic to feet shoulder-width apart (though this facing the floor (25). It requires advanced. To perform the basic side exercise also can be performed from a coactivation of the quadriceps, hamstrings, bridge, lie on one side, with head and chest tandem stance). Grasp the handle (set at gluteals, back extensors, abdominals, propped up over the forearm. The forearm about shoulder level) with both hands, and latissimus dorsi, and pectoral muscles to should be perpendicular to the torso and pull diagonally toward one hip, as during a maintain a steady, hollowed body position. elbow directly under the shoulder, flexed pull toward a slalom buoy. It has been

August 2007 • Strength and Conditioning Journal 50 recommended that cable chops be Additional Considerations for These responses help protect against performed with loads that permit no fewer Training and Injury Prevention cold injury but may interfere profoundly than 8–10 repetitions, due to their large arc The importance of warm-up exercise with physical performance; they are of motion (16). cannot be overstated for slalom water especially exaggerated in cold water, skiers. A proper warm-up increases where rates of heat transfer may be 25 Wall Slides / Dock Slides blood flow to working muscles, which in times greater than in air of the same Because falls during slalom skiing can turn enhances nutrient supply, tissue temperature (59). impose tremendous impact and distraction oxygenation, and waste removal (9, 21). forces on the arms and shoulders, it is It facilitates motor unit recruitment, The body’s initial defense against heat loss is to cause widespread critical for the scapular musculature to which directly affects the rate and force vasoconstriction in the extremities (85). provide as strong a base of support as of muscle contractions (7, 67, 81), and Peripheral vasoconstriction shunts blood possible for the upper extremity. Two may prolong time to fatigue (31). It raises toward the body’s core, thereby limiting simple exercises for conditioning the muscle and core body temperature, its release of heat at the body surface. scapular stabilizers can be performed promoting oxygen-hemoglobin Although this helps preserve core either standing against a wall (34) or lying dissociation at the tissues, faster nerve temperature, it also reduces blood flow on the ground. To strengthen the external impulse conduction, and increased joint to the working muscles, reducing their rotators, stand back to a wall or lie supine range of motion (9, 42, 82). Warmup also on the ground. Raise the arms overhead is believed to help athletes mentally temperature, extensibility, and nerve and press the scapulae and backs of the prepare for their events, possibly by conduction velocity. These effects may significantly diminish strength, power, arms and hands firmly against the wall or influencing arousal and focusing speed, reaction time, dexterity, tactile ground. Slowly slide the arms and hands attention (2, 8, 95). In summary, through sensitivity, and postural control (17, 29, down the wall (like performing a lat pull- several mechanisms, a proper warm-up 35, 53), all of which could alter the down) or along the ground (like making a may enhance muscular coordination, outcome of a slalom pass. snow angel) while continuing to maintain strength, power, reaction time, flexibility, as much contact and pressure as possible. and concentration (9, 28, 73, 74, 77). Once the upper arms reach the sides, Secondary defenses against heat loss include voluntary and involuntary reverse the motion. Carry out 2–3 sets of Unfortunately, many water skiers move 10–15 repetitions. from sedentary roles as spotters and boat muscular action—physical activity and drivers to intense sport activity without shivering (61, 85). Ironically, both increase metabolic heat production, but also To target the internal rotators, stand warming up at all, let alone warming up undermine heat retention, by inducing facing a wall or lie prone on the ground. to support peak athleticism. Skiers who muscular vasodilation and sabotaging the Repeat the motion of the external omit a proper warm-up may not only effectiveness of peripheral rotation exercise, pressing the anterior relinquish performance benefits, but vasoconstriction. Physical activity also surfaces of the arms and hands against suffer outright decrements when cold increases convective heat loss, because the wall or ground. Carry out 2–3 sets of water, cold air, and wind exposure move limb movements accelerate the flow of 10–15 repetitions. the body further from the warmed state. water and air over the body surface. Thus, Many factors influence the degree to Other Slalom-Specific Exercises and which cold exposure affects individuals, if preservation of core temperature General Conditioning including water and air temperature, becomes the body’s priority, restricted Several traditional resistance training duration of exposure, water turbulence muscle blood flow may impair performance. If continuing to perform exercises also can be modified for slalom and wind speed, body fat and surface-to- becomes priority, core body temperature ski training by incorporating an mass ratio, metabolic rate, and presence may drop and its associated anesthetic alternated grip, as is used in holding the or absence of insulative clothing (61, 85, effects (35) may limit performance. towrope handle. Seated rows and pullups 94), but even environmental are good examples. An added benefit of temperatures only slightly below body this modification is that its novelty can Cold exposure also may increase skiers’ temperature (36–37°C, 96.8–98.6°F) will enhance motivation and enjoyment and susceptibility to musculoskeletal injury. cause heat loss from bare-skinned thereby indirectly contribute to muscular Cold water immersion reduces the individuals. Heat loss, in turn, will initiate development. extensibility of soft tissues (35, 94)—an multiple thermoregulatory responses adverse effect for any skier who falls and aimed at preserving core temperature. inadvertently forces a joint through an

August 2007 • Strength and Conditioning Journal 51 unaccustomed range of motion. Because (forward, lateral), push-ups, “supermans,” 6. BELL, F. Principles of Mechanics and warming reduces muscle stiffness (62, 69) curl-ups, leg kicks (forward, backward, Biomechanics. Cheltenham, UK: Stanley and allows greater lengthening before lateral), and marching to raise muscle Thornes, 1998. failure (73), a proper warm-up is strongly temperature and oxygen consumption as 7. BERGH, U., AND B. EKBLOM. Influence recommended to help reduce risks of much as possible. of muscle temperature on maximal injury. Of course, to prevent undermining muscle strength and power output in the positive effects of a proper warm-up, Conclusion human skeletal muscles. Acta Physiol. cold exposure should be limited to Slalom water skiing is an extremely Scand. 107:33–37. 1979. reasonable time frames and insulative demanding technical event, requiring a 8. BISHOP, D. Warm-up I: Potential clothing should be worn when unique blend of strength, power, mechanisms and the effects of passive appropriate. Wet suits and dry suits endurance, timing, coordination, and warm-up on exercise performance. preserve body heat by reducing convective balance. For individuals seeking to realize Sports Med. 33:439–454. 2003. heat loss and should be worn when cold their skiing potential, dryland conditioning 9. BISHOP, D. Warm-up II: Performance stress is severe enough to elicit shivering must be considered essential. Attempting changes following active warm-up and and numbness. Many skiers complain to ski into shape can both slow progress how to structure the warm-up. Sports about the added bulk of these suits, but and increase susceptibility to injury. Med. 33:483–498. 2003. any movement resistance they impose is Dryland training should be used to 10. BLACKWOOD, B. Clean variation for likely to be less detrimental to prehabilitate injury-prone muscles and enhanced performance. Strength Cond. performance than significant cold stress joints, to enhance on-the-water training, to J. 26(4):74–76. 2004. would be. Further research should address correct muscular imbalances arising from 11. BLAIR, S.N., H.W. KOHL III, R.S. PAF- the effects of insulative clothing on motor skiing, and to minimize losses of FENBARGER JR, D.G. CLARK, K.H. performance. neuromuscular adaptations during the off- COOPER, AND L.W. GIBBONS. Physical An ideal warm-up for short-term, season. A variety of modifications to fitness and all-cause mortality: A highintensity events, such as slalom water traditional exercises can enhance both prospective study of healthy men and skiing, should be of an intensity and specificity of training and motivation to women. JAMA. 262:2395–2401. duration sufficient to raise muscle condition. ♦ 1989. temperature and baseline oxygen References 12. BLASIER, R.B., AND L.G. MORAWA. consumption, but not to cause significant 1. ANDERSEN, R.E., AND D.L. Complete rupture of the hamstring fatigue, lactate accumulation, or depletion MONTGOMERY. Physiology of Alpine origin from a water skiing injury. Am. of high-energy phosphates immediately skiing. Sports Med. 6:210–221. 1988. J. Sports Med. 18:435–437. 1990. prior to performance (9). In general, some 2. ANSHEL, M.H.The effect of arousal on 13. BRODY, L.T. Balance impairment. In: form of aerobic activity should be carried warm-up decrement. Res. Q. Exerc. Therapeutic Exercise: Moving Towards out for 5–10 minutes, followed by several Sport. 56:1–9. 1985. Function. D. Hall and L. Brody, eds. minutes of sport-specific exercises and 3. ARIEL, B.G. Biomechanical analysis of Philadelphia: Lippincott Williams & stretches, targeting the prime movers of the knee joint during deep knee bends Wilkins, 1999. pp. 112–127. the athletic task to be performed. Precise with heavy load. In: Biomechanics IV. 14. BROWN, S.L., AND J.G. WILKINSON. specifications will depend on the task, the R.C. Nelson and C. Morehouse, eds. Characteristics of national, divisional, fitness profile of the individual, the Baltimore: University Park Press, and club male Alpine ski racers. Med. environmental conditions, and any 1974. pp. 44–52. Sci. Sports Exerc. 15:491–495. 1983. constraints imposed by the location, 4. ARUIN, A.S., T. OTA, AND M.L. 15. CHAKRAVARTHY, J., N. RAMISETTY, A. organization, or rules of the event. For IMPALNERKAR AND OHTADI LATASH. Anticipatory postural P , N. M . many slalom skiers, location constraints adjustments associated with lateral Surgical repair of complete proximal impose the greatest barrier to achieving a and rotational perturbations during hamstring tendon ruptures in water proper warm-up. Skiers who wait their standing. J. Electromyogr. Kinesiol. skiers and bull riders: A report of four turns to ski on a dock or in a boathouse 11:39–51. 2001. cases and review of the literature. Br. can warm-up as recommended, but skiers 5. BANTA, J.V. Epidemiology of J. Sports Med. 39:569–572. 2005. who wait their turns seated in a boat are waterskiing injuries. West. J. Med. 16. COOK, G., AND K. FIELDS. Functional presented with a greater challenge. Such 130:493– 497. 1979. training for the torso. Strength Cond. skiers are advised to perform multiple, 19(2):14–19. 1997. complex exercises, such as squats, lunges

August 2007 • Strength and Conditioning Journal 52 17. CORNWALL, M.W. Effect of 27. GARDNER, P.J., AND D. COLE. The Characteristics of water skiing–related temperature on muscle force and rate stiff-legged deadlift. Strength Cond. J. and wakeboarding-related injuries of muscle force production in men 21(5):7–14. 1999. treated in emergency departments in and women. J. Orthop. Sports Phys. Ther. 28. GARRETT, W.E. JR. Muscle strain the United States, 2001–2003. Am. J. 20:74–80. 1994. injuries. Am. J. Sports Med. 24(Suppl. Sports Med. 33:1065–1070. 2005. 18. COWLING, E.J., AND J.R. STEELE. Is 6):S2–S8. 1996. 37. HUMMEL, G., AND B.J. GAINOR. lower limb muscle synchrony during 29. GIESBRECHT, G.G., M.P. WU, M.D. Waterskiing-related injuries. Am. J. landing affected by gender? WHITE, C.E. JOHNSTON, AND G.K. Sports Med. 10:215–218. 1982. Implications for variations in ACL BRISTOW. Isolated effects of 38. HURD, W.J., T.L. CHMIELEWSKI, AND L. injury rates. J. Electromyogr. Kinesiol. 11: peripheral arm and central body SNYDER-MACKLER. 263–268. 2001. cooling on arm performance. Aviat. Perturbationenhanced neuromuscular 19. DUFFIELD, R., B. DAWSON, AND C. Space Environ. Med. 66:968–975. training alters muscle activity in GOODMAN. Energy system 1995. female athletes. Knee Surg. Sports contribution to 100-m and 200-m 30. GOODWIN, G.M., D.I. MCCLOSKEY, Traumatol. Arthrosc. 14:60–69. 2006. track running events. J. Sci. Med. Sport. AND J.H. MITCHELL. Cardiovascular 39. HYDOCK, D. The split position: Sport 7:302– 313. 2004. and respiratory responses to changes specificity with a barbell. Strength Cond. 20. EBERHARDT, T. An anatomical in central command during isometric 19(5):56–59. 1997. description of the slalom turn in water exercise at constant muscle tension. J. 40. INTERNATIONAL WATER SKI skiing and how to condition for this Physiol. 226:173–190. 1972. FEDERATION. IWSF Records. 2006. sport. NSCA J. 10(6):4–9. 1988. 31. GORASSINI, M., J.F. YANG, M. SIU, AND Available at: 21. ELAM, R. Warm-up and athletic D.J. BENNETT. Intrinsic activation of http://www.iwsf.com/history/ performance: A physiological analysis. human motoneurons: Reduction of rechist.htm. Accessed July 13, 2006. NSCA J. 8(2):30–33. 1986. motor unit recruitment thresholds by 41. INTERNATIONAL WATER SKI FEDERA- 22. FABROCINI, B.The planning of a repeated contractions. J. Neurophysiol. TION TOURNAMENT COUNCIL. powerful trunk for tennis. Strength 87:1859–1866. 2002. International Water Ski Federation Cond. 17(5):25–29. 1995. 32. GRACE, N. Water skiing hazards: 2006 Tournament water ski rules. 23. FIG, G. Strength training for Nature and prevention. Sports Med. 2006. Available at: swimmers: Training the core. Strength 2:212–216. 1974. http://www.iwsf.com/ Cond. J. 27(2):40–42. 2005. 33. GRACE, N., R. OUTERBRIDGE, J.F. PEP- rules2004/rulebook2004/rules06v1 24. FRANKE, W.D., C.F. BOETTGER, PER, AND W. SOKOLOWSKI. Water .0 .htm#14.03. Accessed July 13, ANDS.P. MCLEAN. Effects of varying skiing. In: Sports Injuries: Mechanisms, 2006. central command and muscle mass on Prevention, Treatment. F.H. Fu and 42. JONES, A.M., K. KOPPO, ANDM. the cardiovascular responses to D.A. Stone, eds. Philadelphia: BURNLEY.Effects of prior exercise on isometric exercise. Clin. Physiol. Lippincott Williams & Wilkins, metabolic and gas exchange responses 20:380–387. 2000. 2001. pp. 804–817. to exercise. Sports Med. 33:949–971. 25. FREDERICSON, M., W. MOORE, M. 34. HALL, C. The shoulder girdle. In: 2003. GUILLET, ANDC. BEAULIEU.High Therapeutic Exercise: Moving Towards 43. KEOGH, J. Lower-body resistance hamstring tendinopathy in runners: Function. D. Hall and L. Brody, eds. training: Increasing functional Meeting the challenges of diagnosis, Philadelphia: Lippincott Williams & performance with lunges. Strength treatment, and rehabilitation. Phys. Wilkins, 1999. pp. 575–625. Cond. J. 21(1):67–72. 1999. Sportsmed. [serial online]. 33(5). 2005. 35. HOFFMAN, R.G. Human psychological 44. KEVERLINE, J.P., R. ENGLUND, AND Available at: performance in cold environments. T.E. COONEY.Takeoff forces http://www.physsportsmed.com/ In: Medical Aspects of Harsh transmitted to the upper extremity issues/2005/0505/fredericson.htm. Environments: Vol I. D.E. Lounsbury during water-skiing. Orthopedics. Accessed May 14, 2006. and R.F. Bellamy, eds. Washington, 26:707– 710. 2003. 26. FRY, A.C., J.C. SMITH, AND B.K. DC: Dept. of the Army, Office of 45. KIRBY, R.L., N.A. PRICE, AND D.A. SCHILLING. Effect of knee positions the Surgeon General, 2002. pp. 383– MACLEOD. The influence of foot on hip and knee torques during the 408. position on standing balance. J. barbell squat. J. Strength Cond. Res. 36. HOSTETLER, S.G., T.L. HOSTETLER, Biomech. 20:423–427. 1987. 17:629–633. 2003. G.A. SMITH, AND H. XIANG. 46. LEGGETT, S.H., M.N. FULTON, M.L.

August 2007 • Strength and Conditioning Journal 53 POLLOCK, D.M. CARPENTER, J.E. 55. MCGILL, S., D. JUKER, AND P. KROPF. 64. PATERSON, D.C. Water-skiing injuries. GRAVES, M.B. SHANK, A. ENGMANN, Quantitative intramuscular Practitioner. 206:655–661. 1971. AND D. KAUFMAN. Physiological myoelectric activity of quadratus 65. PIPER, T.J., AND M.A. WALLER. evaluation of professional water lumborum during a wide variety of Variations of the deadlift. Strength skiers. J. Strength Cond. Res. 8:20–27. tasks. Clin. Biomech. 11:170–172. 1996. Cond. J. 23(3):66–73. 2001. 1994. 56. MCGILL, S.M Developing the exercise 66. POLLOCK, A.S., B.R. DURWARD, P.J. 47. LEGGETT, S.H., K. KENNEY, AND T. program. In: Low Back Disorders: ROWE, AND J.P. PAUL.What is balance? EBERHARDT. Applied physiology of Evidence-Based Prevention and Clin. Rehabil. 14:402–406. 2000. water-skiing. Sports Med. 21:262– 276. Rehabilitation. Champaign, IL: Human 67. RACINAIS, S., S. BLONC, AND O. HUE. 1996. Kinetics, 2002. pp. 239–257. Effects of active warm-up and diurnal 48. LEFEVER-BUTTON, S. Closed kinetic 57. MITCHELL, J.H., AND R.F. SCHMIDT. increase in temperature on muscular chain training. In: Therapeutic Exercise: Cardiovascular reflex control by power. Med. Sci. Sports Exerc. 37: Moving Towards Function. D. Hall and L. afferent fibers from skeletal muscle 2134–2139. 2005. Brody, eds. Philadelphia: Lippincott receptors. In: Handbook of Physiology, 68. ROBERTS, S.N., AND P.M. ROBERTS. Williams & Wilkins, 1999. pp. 252– Section 2: The Cardiovascular System, Tournament water skiing trauma. Br. 273. Volume III: Peripheral Circulation and J. Sports Med. 30:90–93. 1996. 49. LUTZ, G.E., R.A. PALMITIER, K.N. AN, Organ Blood Flow, Part 2. J.T. Shepherd, 69. ROBERTSON, V.J., A.R. WARD, AND P. AND E.Y. CHAO. Comparison of ed. Bethesda, MD: American JUNG. The effect of heat on tissue tibiofemoral joint forces during Physiology Society, 1983. pp. 638– extensibility: A comparison of deep openkinetic-chain and closed-kinetic- 658. and superficial heating. Arch. Phys. chain exercises. J. Bone Joint Surg. Am. 58. MYKLEBUST, G., L. ENGEBRETSEN, I.H. Med. Rehabil. 86:819–825. 2005. 75:732–739. 1993. BRAEKKEN, A. SKJOLBERG, O.E. 70. ROWELL, L.B., AND D.S. O’LEARY. 50. MACWILLIAMS, B.A., D.R. WILSON, OLSEN, AND R. BAHR. Prevention of Reflex control of the circulation J.D. DESJARDINS, J. ROMERO, AND E.Y. anterior cruciate ligament injuries in during exercise: Chemoreflex and CHAO. Hamstrings cocontraction female team handball players: A mechanoreflexes. J. Appl. Physiol. reduces internal rotation, anterior prospective intervention study over 69:407–418. 1990. translation, and anterior cruciate three seasons. Clin. J. Sport Med. 71. ROWELL, L.B., D.S. O’LEARY, AND ligament load in weight-bearing 13:71–78. 2003. D.L. KELLOGG. Integration of flexion. J. Orthop. Res. 17:817–822. 59. NADEL, E.R., I. HOLMER, U. BERGH, cardiovascular control systems in 1999. P.O. ASTRAND, AND J.A. STOLWIJK. dynamic exercise. In: Handbook of 51. MAKDISSI, M. Posterior thigh pain— Energy exchanges of swimming man. Physiology, Section 12: Exercise: Regulation Water skiing. Med. Sci. Sports Exerc. J. Appl. Physiol. 36:465–471. 1974. and Integration of Multiple Systems. L.B. 35:S160. 2003. 60. NEUMAYR, G., H. HOERTNAGL, R. Rowell and J.T. Shepherd, eds. 52. MAKI, B.E., AND W.E. MCILROY. The PFISTER, A. KOLLER, G. EIBL, AND E. Bethesda, MD: American Physiology role of limb movements in RAAS. Physical and physiological Society, 1996. pp. 770–838. maintaining upright stance: The factors associated with success in 72. RUSKO, H., M. HAVU, E. KARVINEN. “change-insupport” strategy. Phys. professional Alpine skiing. Int. J. Sports Aerobic performance capacity in Ther. 77: 488–507. 1997. Med. 24:571–575. 2003. athletes. Eur. J. Appl. Physiol. Occup. 53. MAKINEN, T.M., H. RINTAMAKI, J.T. 61. NOAKES, T.D. Exercise and the cold. Physiol. 38:151–159. 1978. KORPELAINEN, V. KAMPMAN, T. Ergonomics. 43:1461–1479. 2000. 73. SAFRAN, M.R., W.E. GARRETT JR, A.V. PAAKKONEN, J. OKSA, L.A. PALINKAS, 62. NOONAN, T.J., T.M. BEST, A.V. SEABER, R.R. GLISSON, AND B.M. J. LEPPALUOTO, AND J. HASSI. Postural SEABER, AND W.E. GARRETT JR. RIBBECK.The role of warm-up in sway during single and repeated cold Thermal effects on skeletal muscle muscular injury prevention. Am. J. exposures. Aviat. Space Environ. Med. tensile behavior. Am. J. Sports Med. Sports Med. 16:123–129. 1988. 76:947–953. 2005. 21:517– 522. 1993. 74. SAFRAN, M.R., A.V. SEABER, AND W.E. 54. MCARDLE, W.D., KATCH, F.L., AND 63. NORKIN, C.C., AND P.K. LEVANGIE. GARRETT JR. Warm-up and muscular V.L. KATCH. Exercise Physiology: Energy, Posture. In: Joint Structure and Function: injury prevention: An update. Sports Nutrition and Human Performance (5th A Comprehensive Analysis (2nd ed.). Med. 8:239–249. 1989. ed.). Philadelphia: Lippincott Williams Philadelphia: F.A. Davis, 1992. 75. SALLAY, P.I., R.L. FRIEDMAN, P.G. & Wilkins, 2001. p. 759. pp. 419–447. COOGAN, AND W.E. GARRETT.

August 2007 • Strength and Conditioning Journal 54 Hamstring muscle injuries among Institute of Environmental Medicine, 95. WRISBERG, C.A., ANDM.H. ANSHEL.A water skiers: Functional outcome and 1988. pp. 361–399. field test of the activity-set hypothesis prevention. Am J. Sports Med. 24:130– 86. TOUTOUNGI, D.E., T.W. LU, A. LEAR- for warm-up decrement in an open 136. 1996. DINI, F. CATANI, AND J.J. O’CONNOR. skill. Res. Q. Exerc. Sport. 64:39–45. 76. SEATON, P., ANDD. EMERY.Waterskiing. Cruciate ligament forces in the human 1993. Boston: Faber & Faber, 1979. p. 22. knee during rehabilitation. Clin. 77. SHELLOCK, F.G., AND W.E. PRENTICE. Biomech. 15:176–187. 2000. Warming-up and stretching for 87. VEICSTEINAS, A., G. FERRETTI, V. improved physical performance and MARGONATO, G. ROSA, AND D. prevention of sports-related injuries. TAGLIABUE. Energy costs of and Sports Med. 2:267–278. 1985. energy sources for Alpine skiing in top 78. SPEER, K.P. Anatomy and athletes. J. Appl. Physiol. 56:1187– pathomechanics of shoulder 1190. 1984. instability. Clin. Sports Med. 14:751– 88. VERBURG, H., AND J.N. KEEMAN. 760. 1995. Complete rupture of the tendon of the Mullins 79. SPENCER, M.R., AND P.B. GASTIN. biceps muscle of the thigh. Ned. Energy system contribution during Tijdschr. Geneeskd. 135:1970–1971. Nicole Mullins is an assistant professor in 200to 1500-m running in highly 1991. the Department of Human Performance trained athletes. Med. Sci. Sports Exerc. 89. VOGT, M., K. JORDAN, H. SPRING, AND and Exercise Science at Youngstown State 33: 157–162. 2001. H. HOPPELER. Muscle physiology and University. 80. STANISAVLJEVIC, S., R.B. IRWIN, AND determinants of performance in elite L.R. BROWN. Orthopedic injuries in Alpine skiers. Med. Sci. Sports Exerc. water-skiing: Etiology and prevention. 35:S93. 2003. Orthopedics. 1:125–129. 1978. 90. WHITE, A.T., AND S.C. JOHNSON. 81. STEWART, D., A. MACALUSO, AND G. Physiological comparison of DE VITO. The effect of an active international, national and regional warm-up on surface EMG and muscle Alpine skiers. Int. J. Sports Med. performance in healthy humans. Eur. 12:374– 378. 1991. J. Appl. Phys. 89:509–513. 2003. 91. WILK, K.E., R.F. ESCAMILLA, G.S. 82. STEWART, I.B., AND G.G. SLEIVERT. FLEISIG, W.S. BARRENTINE, J.R. AN- The effect of warm-up intensity on DREWS, AND M.L. BOYD. A range of motion and anaerobic comparison of tibiofemoral joint performance. J. Orthop. Sports Phys. forces and electromyographic Ther. 27:154–161. 1998. activity during open and closed 83. TESCH, P.A. Aspects on muscle kinetic exercises. Am. J. Sports Med. properties and use in competitive 24:518–527. 1996. Alpine skiing. Med. Sci. Sports Exerc. 92. WILLIAMSON, J.W., R. MCCOLL, D. 27:310– 314. 1995. MATHEWS, M. GINSBURG, AND J.H. 84. TESCH, P.A., L. LARSSON, A. ERIKSSON, MITCHELL. Activation of the insular AND J. KARLSSON. Muscle glycogen cortex is affected by the intensity of depletion and lactate concentration exercise. J. Appl. Physiol. 87:1213– during downhill skiing. Med. Sci. Sports. 1219. 1999. 10:85–90. 1978. 93. WINTER, D.A., A.E. PATLA, F. PRINCE, 85. TONER, M.M., AND W.D. MCARDLE. M. ISHAC, AND K. GIELO-PERCZAK. Physiological adjustments of man to Stiffness control of balance in quiet the cold. In: Human Performance standing. J. Neurophysiol. 80:1211– Physiology and Environmental Medicine at 1221. 1998. Terrestrial Extremes. K.B. Pandolf, 94. WITTMERS, L.E. JR. Pathophysiology M.N. Sawka, and R.R. Gonzalez, eds. of cold exposure. Minn. Med. Alexandria, VA: U.S. Army Research 84(11):30–36. 2001.

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