THE EFFECT OF LOWER LIMB LOADING ON ECONOMY AND KINEMATICS OF SKATE ROLLER SKIING by Tyler Johnson Reinking A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Health and Human Development MONTANA STATE UNIVERSITY Bozeman, Montana May 2014 ©COPYRIGHT by Tyler Johnson Reinking 2014 All Rights Reserved ii TABLE OF CONTENTS 1. INTRODUCTION ...................................................................................................1 Load Carriage...........................................................................................................3 Limb Velocity ..........................................................................................................6 Purpose .....................................................................................................................8 Hypotheses ...............................................................................................................9 Delimitations ..........................................................................................................10 Limitations .............................................................................................................10 Assumptions ...........................................................................................................11 Operational Definitions ..........................................................................................11 2. LITERATURE REVIEW ......................................................................................14 Introduction ............................................................................................................14 Economy ................................................................................................................15 Load Carriage.........................................................................................................16 Kinematics .............................................................................................................18 The Effect of Equipment Mass on Oxygen Consumption .....................................20 Cycle Rate Variation ..............................................................................................24 Treadmill Speed and Grade to Manipulate Kinematics .........................................25 Conclusion .............................................................................................................26 3. THE EFFECT OF LOWER LIMB LOADING ON ECONOMY AND KINEMATICS OF SKATE ROLLER SKIING ..........................................27 Contributions of Authors and Co-Authors .............................................................27 Manuscript Information Page ................................................................................28 Abstract ..................................................................................................................29 Introduction ............................................................................................................30 Methods..................................................................................................................33 Study Design ....................................................................................................33 Subjects ............................................................................................................33 Testing Procedures ...........................................................................................34 Work Rate Selection ........................................................................................36 Justification for Limb-Loading Conditions .....................................................36 Instrumentation ................................................................................................37 Roller Skiing Equipment............................................................................37 Indirect Calorimetry ...................................................................................37 Lactate Testing ...........................................................................................37 Data Processing ................................................................................................38 Statistical Analysis ...........................................................................................38 Pilot Testing .....................................................................................................39 iii TABLE OF CONTENTS – CONTINUED Results ....................................................................................................................40 Subjects ............................................................................................................40 Physiological Variables ...................................................................................40 Reliability Analysis ..........................................................................................41 Cycle Rate ........................................................................................................43 Discussion ..............................................................................................................44 Physiological Variables ...................................................................................44 Primary Analysis ........................................................................................44 Sub-Analysis ..............................................................................................45 Reliability ...................................................................................................45 Cardiovascular Drift...................................................................................46 Cycle Rate ........................................................................................................51 Future Considerations ......................................................................................52 Conclusions ......................................................................................................53 4. CONCLUSIONS....................................................................................................55 REFERENCES CITED ................................................................................................58 APPENDICES .............................................................................................................64 APPENDIX A: Subject Consent Form ...........................................................65 APPENDIX B: Health History Quesionnaire .................................................71 iv LIST OF TABLES Table Page 2.1 Effect of added mass on running and walking studies. Percent differences in oxygen consumption (VO2) from the control condition have been standardized to the observed increase per 100 grams per foot ......................................................................................23 3.1 Mean oxygen consumption (VO2) and heart rate (HR) for a subject with four different limb loads during a pilot test. The percent difference in VO2 from the control condition is also listed. ............................................................39 3.2 Subject Demographics (Mean±SD) .....................................................40 3.3 Physiological values (Mean ± SE) observed at each limb load condition for both low (L) and high (H) work rates. ...................41 3.4 Physiological variables by testing sequence and work rate (Mean ± SE) .................................................................41 3.5 ANOVA p-values comparing the mean values for physiological variables during the fourth minute with the same values from the fifth minute at each test stage. Note that each skier performed only one of the work rates for each stage (i.e., either 1 (L) or 1 (H) but not both) for a total of 8 of the 16 stages .............................................42 v LIST OF FIGURES Figure Page 3.1 Mean (±SE) cycle rate values for each limb load condition at both high and low work rates. Cycle rates at the low work rate were all statistically lower (p<0.05) than those at the high work rates ...........................................43 vi ABSTRACT It has been proposed that skate skiing economy and racing performance have improved as a result of lighter equipment. Despite the many studies that have found running and walking economy to improve with lighter shoes, there are no published studies that show any relationship between the mass of skate skiing equipment and markers of skate skiing performance. To investigate the effects of skate skiing equipment mass on markers of performance, this study added mass to the lower limbs of skate roller skiers and measured changes in economy and gross movement kinematics. Twelve male (Mean±SD; Age (yrs): 21.4±3.9) and eight female (Mean±SD; Age (yrs): 19.9±2.2) competitive cross-country skiers completed two laboratory visits to roller ski on an oversized treadmill. In the first visit, subjects completed a graded exercise test to determine their lactate threshold. In the second visit, subjects completed 5 minutes of roller skiing at a low work rate (2 m/s for women and 3 m/s for men both at 2⁰) and a high work rate (2 m/s for women and 3 m/s for men both at 3.15⁰) for each of the four limb loading conditions (0 g, 200 g, 400 g, and 600 g). Oxygen consumption (VO2), heart rate (HR), and cycle rate were measured during the last 2 minutes of each stage and