<p> 1 Improving Bone Density | 1 2 1Article Type: Commentary</p><p>2</p><p>3Article Category: Sports Fitness and Health</p><p>4</p><p>5Title: Training to Improve Bone Density in Adults: A Review and Recommendations</p><p>6</p><p>7Running Head: Improving Bone Density</p><p>8</p><p>9Authors: Ed McNeely</p><p>10</p><p>11Corresponding Author:</p><p>12Ed McNeely, MS</p><p>13One Academy Drive</p><p>14Daphne Al, 36526</p><p>[email protected]</p><p>16555-555-5555</p><p>17</p><p>18Ed McNeely is the senior physiologist at the Peak Centre for Human Performance and a partner </p><p>19in StrengthPro Inc. a Las Vegas based sport and fitness consulting company he is also a National </p><p>20Faculty member of the United States Sports Academy</p><p>21</p><p>22</p><p>23</p><p>24 3 Improving Bone Density | 2 4 25Training to Improve Bone Density in Adults: A Review and Recommendations</p><p>26</p><p>27</p><p>28</p><p>29</p><p>30</p><p>31</p><p>32</p><p>33</p><p>34</p><p>35</p><p>36</p><p>37</p><p>38</p><p>39</p><p>40</p><p>41</p><p>42</p><p>43</p><p>44</p><p>45</p><p>46</p><p>47 5 Improving Bone Density | 3 6 48ABSTRACT</p><p>49 The loss of bone density is becoming a major health concern in industrialized </p><p>50societies. Increasing bone density during puberty and young adulthood is considered the </p><p>51best option for preventing the negative health consequences associated with osteoporosis,</p><p>52even in middle aged and older adults an exercise program can increase bone density. </p><p>53While low volume impact oriented aerobic activities like running have been shown to be </p><p>54effective at increasing bone density excessive endurance training has been linked to low </p><p>55bone density. Strength training remains the best option for adults wishing to increase </p><p>56bone density. A regular program of high load (60-85% 1RM) training three or more times</p><p>57per week using a variety of exercises that challenge all major muscles has been shown to </p><p>58significantly increase bone density even in elderly adults.</p><p>59</p><p>60Key words: bone density, exercise, osteoporosis, training</p><p>61</p><p>62</p><p>63</p><p>64</p><p>65</p><p>66</p><p>67</p><p>68</p><p>69</p><p>70</p><p>71</p><p>72 7 Improving Bone Density | 4 8 73INTRODUCTION</p><p>74 Osteoporosis, which has been defined as bone mineral density (BMD) more than 2.5 </p><p>75standard deviations below the young adult mean value (14), is a growing health problem for both </p><p>76men and women. In developed and developing countries the incidence of osteoporosis is </p><p>77increasing at a rate faster than what would be predicted by the aging of the population alone (15). </p><p>78In the U.S. It has been estimated that by 2025 the number of hip fractures attributed to </p><p>79osteoporosis will double to nearly 2.6 million with a greater percentage increase in men than in </p><p>80women (12). </p><p>81 Epidemiological evidence suggests that genetic factors are the most important cause of </p><p>82osteoporosis (20) and can account for as much as 80% of the variability in bone density in the </p><p>83population (6) but a variety of environmental factors have been linked to bone density including: </p><p>84negative energy balance, low calcium intake, lack of fruit and vegetable consumption, low body </p><p>85mass index, strength, and hormone levels (13,22,9,7,23), all of which may influence the ability to</p><p>86develop or maintain bone density.</p><p>87 A well designed exercise can have a tremendous impact on bone, increasing density, size </p><p>88and mechanical strength (23) and may be one of the keys to preventing complications associated </p><p>89with osteoporosis. If bone density and maximum tensile strength are increased before </p><p>90osteoporosis sets in, subsequent complications could be minimized (21). Unfortunately many </p><p>91adults wait to start an exercise program once they are diagnosed with low bone density. </p><p>92 For middle aged and older adults one of the primary health goals of an exercise program </p><p>93is to maintain bone density. Without an exercise intervention, after the age of 40 bone mass </p><p>94decreases by about 0.5% per year, regardless of sex or ethnicity (15). Whether appreciable </p><p>95increases in bone density can occur for this age group is equivocal (15) and dependant on the </p><p>96duration of the exercise program, age, dietary factors, and history of physical activity. A variety </p><p>97of different types of exercise have been used in bone building programs middle aged or older </p><p>98adults. 9 Improving Bone Density | 5 10 99Training Techniques</p><p>100Strength training </p><p>101 Although not all studies have shown improvement in bone density with strength training </p><p>102(15), strength training, if done with a high enough intensity for a prolonged period of time, seems </p><p>103to be effective for improving bone density in middle aged and older women who have low bone </p><p>104density (16). Programs that have been successful at increasing bone density have several common</p><p>105characteristics; training intensity above 70% 1RM, programs that last more than 12 months, and </p><p>106training frequency greater than two times per week.</p><p>107 </p><p>108Endurance Training </p><p>109 Endurance training can be an acceptable form of exercise for maintaining or increasing </p><p>110bone density in middle aged or older adults provided there is sufficient impact. Stuart and Hannan</p><p>111(22) examined the effects of cycling, running or both on bone density in recreational male </p><p>112athletes. They found that runners had greater total and leg BMD than controls, those athletes </p><p>113participating in both cycling and running had greater total and arm BMD whereas the cyclists had</p><p>114decreased spine BMD compared to controls. The lack of impact involved in cycling may explain </p><p>115the lack of change in BMD even though all groups performed equal volumes of work throughout </p><p>116the study period. Walking programs, because of their low impact, tend to show only modest or no</p><p>117effects on BMD (3,18). Rowing because of the high compressive and shear forces placed on the </p><p>118spine, 4.6 times body weight, has been shown to increase lumbar spine BMD but not at other </p><p>119areas (17). Moderate training volumes seem to be more effective for increasing bone density. </p><p>120Running mileage of 20-30 km per week has a positive effect on bone, particularly lower leg and </p><p>121distal femur, but training volumes greater than this may cause a chronic increase in cortisol that </p><p>122negatively impacts bone (4) and running 92 km per week has been shown to result in bone </p><p>123density lower than sedentary controls (2).</p><p>124 11 Improving Bone Density | 6 12 125Jump Training </p><p>126 Although effective and popular in school based programs for increasing bone density in </p><p>127younger people jump training does not appear to be as effective in middle aged and older women.</p><p>128In a study comparing the effects of 12 months of vertical jumping on spine and proximal femur </p><p>129BMD in a group of pre and post menopausal women, Bassey, Rothwell, Littlewood and Pye </p><p>130(1998) found that 50 jumps six days per week increased BMD in the pre-menopausal group but </p><p>131not in the post menopausal group compared to group specific controls. Interestingly, the lack of </p><p>132change occurred even though the ground reaction forces and rate of force development on landing</p><p>133were higher in the post menopausal group resulting in a greater strain overload than in the pre </p><p>134menopausal group. </p><p>135 While a variety of exercise modalities have proven to be effective at maintaining bone </p><p>136density in adults there some basic principals should be considered when designing a long term </p><p>137program for people with osteoporosis:</p><p>138</p><p>139Exercise Considerations</p><p>140Use a progressive program </p><p>141 Increase resistance and intensity progressively. This is necessary because for bone to </p><p>142form it requires a minimum amount of strain. Once a bone adapts to a given strain level, the </p><p>143stimulus for bone to form is removed and a higher strain level becomes necessary for it to adapt </p><p>144further (10). </p><p>145</p><p>146Use dynamic movements </p><p>147 Mechanical loading of bone has an osteogenic effect only if the loading is dynamic and </p><p>148variable, static loading of bone does not trigger an adaptive response (23). Impact and rapid </p><p>149changes of direction can be particularly effective because ground reaction forces tend to be </p><p>150highest during these activities. Jumps, running, and more explosive or dynamic strength training 13 Improving Bone Density | 7 14 151activities should make up the majority of exercise in a bone building program. In adults with </p><p>152advanced osteoporosis more explosive exercises should be phased in gradually as their </p><p>153conditioning and bone strength improves.</p><p>154</p><p>155Vary the exercises </p><p>156 Bone adaptations occur primarily at insertion and origin points where muscles attach to </p><p>157the bones. Ryan et al. (1994) suggest that increased BMD from strength training and explosive </p><p>158activities is related to the load placed on the muscles that act as prime movers. A wide variety of </p><p>159exercises, which change every 2-4 weeks, exercising the whole body will help ensure that all </p><p>160bones receive stimulus to increase BMC or BMD. </p><p>161</p><p>162Minimum intensity </p><p>163 As with most training there is a minimum level of intensity that is needed to stimulate </p><p>164increase in BMD. For strength training activities there is a linear relationship between weight </p><p>165lifted and improvements in bone density (5) Chilibeck, Sale and Webber (1995) suggest that for </p><p>166strength training intensities of at least 60% 1RM are needed to increase BMD, with faster and </p><p>167greater increases in bone density coming as intensity climbs (16). For impact activities like </p><p>168running and jumping ground reaction forces of greater than two times body weight can increase </p><p>169bone density with higher forces having a greater effect. </p><p>170</p><p>171Training frequency </p><p>172 Improvements in BMD can occur with relatively short training sessions if high impact </p><p>173activities like jumping are the core of the program. However, there is a need to perform these </p><p>174sessions frequently. Studies of jump training have found that where three or more sessions per </p><p>175week is sufficient to increase bone two session per week has negligible effect on bone density </p><p>176(11). 15 Improving Bone Density | 8 16 177</p><p>178Program duration </p><p>179 Consistency is one of the keys to long term bone health. Like other tissues bone </p><p>180undergoes both adaptation to training and detraining during periods of decreased activity. The </p><p>181bone remodelling cycle lasts four to six months (8); this is the minimum period of time needed </p><p>182for BMD to change significantly. Training programs need to be designed so that they offer the </p><p>183variety and adaptability for people to make them a year round part of lifelong fitness regime.</p><p>184</p><p>185CONCLUSIONS</p><p>186 Decreased bone density is a growing problem in modern societies. Exercise remains one </p><p>187of the most potent alternatives to drug treatments for maintaining or improving bone density. An </p><p>188intensive program, three or more times per week featuring a variety of exercises, that considers </p><p>189the individual needs of each person and promotes long term compliance, can have a positive </p><p>190impact on bone density. </p><p>191</p><p>192APPLICATIONS IN SPORT</p><p>193 Over the past years adults have become more and more active in age group sports, </p><p>194particularly in the endurance sports like running, cycling and triathlon. The inclusion of an </p><p>195intensive strength training program will not only improve their performance but help offset the </p><p>196decrease in bone density that often accompanies aging and higher volumes of aerobic </p><p>197training. </p><p>198</p><p>199ACKNOWLEDGMENTS</p><p>200 None</p><p>201 17 Improving Bone Density | 9 18 202REFERENCES</p><p>203 1. Bassey, E. J., Rothwell, M.C., Littlewood, J.J., & Pye, D.W. (1998). Pre- and 204 postmenopausal women have different BMD responses to the same high-impact 205 exercise. J. 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