Most exercise results in some skeletal muscle damage. However, unaccustomed exercise andlor eccentric exercise can cause extensive damage. This exercise-induced muscle damage causes a response that can be characterized by a cascade of metabolic events. Within 24 to 48 hours, delayed onset muscle soreness and weakness, the most obvious manifestations of the damage, peak. Increased circulating neutrophils and interleukin-1 occurs within 24 hours after the exercise, with skeletal muscle levels remaining elevated for a much longer time. There is a prolonged increase in ultrastructural damage and muscle protein degradation as well as a depletion of muscle glycogen stores. These metabolic alterations may result in the increased need for dietary protein, particularly at the beginning of a training program that has a high eccentric component such as strength training. The delay in muscle repair and glycogen repletion following damaging exercise should cause coaches and athletes to allow an adequate period of time between competition for complete recovery.
William J. Evans
William J. Evans, Todd A. Trappe, James D. Fluckey and Charlotte Peterson
Wayne W. Campbell, Lyndon J.O. Joseph, Richard A. Anderson, Stephanie L. Davey, Jeremy Hinton and William J. Evans
This study assessed the effect of resistive training (RT), with or without high-dose chromium picolinate (Cr-pic) supplementation, on body composition and skeletal muscle size of older women. Seventeen sedentary women, age range 54-71 years. BMI 28.8±2.4 kg/m2. were randomly assigned (double-blind) to groups (Cr-pic. n = 9; Placebo, n = 8) that consumed either 924 μg Cr/d as Cr-pic or a low-Cr placebo (<0.2 μg Cr/d) during a 12-week RT program (2 day/ week, 3 sets · exercise−1 · d1,80% of 1 repetition maximum). Urinary chromium excretion was 60-fold higher in the Cr-pic group, compared to the Placebo group (p < .001), during the intervention. Resistive training increased maximal strength of the muscle groups trained by 8 to 34% (p < .001), and these responses were not influenced by Cr-pic supplementation. Percent body fat and fat-free mass were unchanged with RT in these weight-stable women, independent of Cr-pic supplementation. Type I and type II muscle fiber areas of the m. vastus lateralis were not changed over time and were not influenced by Cr-pic supplementation. These data demonstrate that high-dose Cr-pic supplementation did not increase maximal strength above that of resistive training alone in older women. Further, these data show that, under these experimental conditions, whole body composition and skeletal muscle size were not significantly changed due to resistive training and were not influenced by supplemental chromium picolinate.
Wayne W. Campbell, Lyndon J.O. Joseph, Richard E. Ostlund Jr., Richard A. Anderson, Peter A. Farrell and William J. Evans
This study assessed the effects of resistive training (RT) with or without chromium picolinate (Cr-pic) supplementation on the 24-h urinary excretions of myo-inositol, D-chiro-inositol, and pinitol, as well as clinical indices of kidney and liver functions. Thirty-two nondiabetic subjects, age 62 ± 4 y, performed RT twice weekly for 12 wk and consumed either 924 μg Cr/d as Cr-pic (n = 17) or a placebo (n = 15). Whole-body strength increased in all subjects by 20% and urinary chromium excretion increased 47-fold in the Cr-pic group. Urinary myo-inositol, D-chiro-inositol, and pinitol were not changed with RT or influenced by Cr-pic. Serum indices of kidney and liver functions were within clinically normal ranges at baseline and the end of the study. These results suggest that RT did not influence the urinary excretions of inositols. High dose Cr-pic did not influence the urinary excretion of inositols and the selected indices of kidney and liver functions in conjunction with RT
Laura E. Murray-Kolb, John L. Beard, Lyndon J. Joseph, Stephanie L. Davey, William J. Evans and Wayne W. Campbell
To examine the effects of resistance training on hematological and selected indices of iron status in 17 women aged 54–71 years and 18 men aged 56–69 years.
Tests and evaluations were done before and after all subjects participated in a resistance training program twice weekly for 12 weeks.
The resistance training was effective as evidenced by increases in skeletal muscle strength of 20 ± 9% and 23 ± 13% for the men and women, respectively. Hematological parameters and serum iron concentrations were within normal clinical ranges and were unchanged by resistance training for both the men and the women. Total iron binding capacity (TIBC) and transferrin saturation were also unaffected by resistance training in the women but were significantly affected in the men. The men showed a decreased TIBC (p < .0001) and an increased transferrin saturation (p = .050). Serum ferritin concentrations decreased significantly in the women (p = .041) but were unchanged in the men. Transferrin receptor concentrations were unaffected by resistance training in the women but increased significantly in the men (p = .030).
With resistance training, iron status of older men and women changes in a sex specific way.
Alison C. Jozsi, Esther E. Dupont-Versteegden, Jane M. Taylor-Jones, William J. Evans, Todd A. Trappe, Wayne W. Campbell and Charlotte A. Peterson
Studies have been performed in humans to identify changes in gene expression that may account for the relatively weak and variable response of aged muscle to resistance exercise. The gene expression profile of skeletal muscle from elderly (62–75 years old) compared to younger (20–30 years old) men demonstrated elevated expression of genes typical of a stress or damage response. The expression of the majority of these genes was unaffected by a single bout of high-intensity resistance exercise in elderly subjects but was altered acutely by exercise in younger subjects so as to approach the pre-exercise levels observed in older subjects. The inability of muscle from elderly subjects to respond to resistance exercise was also apparent in the expression of inflammatory response genes, which increased within 24 hours of the exercise bout only in younger subjects. Other genes with potentially important roles in the adaptation of muscle to exercise, showed a similar or even more robust response in older compared to younger subjects. Taken together, these results may help to explain the variable hypertrophic response of muscle from older individuals to resistance training.
Michelle M. Porter, Miriam E. Nelson, Maria A. Fiatarone Singh, Jennifer E. Layne, Christine M. Morganti, Isaiah Trice, Christina D. Economos, Ronenn Roubenoff and William J. Evans
Resistance training (RT) increases strength in older adults, but there have been few studies of long-term RT or detraining in older adults. Postmenopausal participants (51–71 years of age) were randomized to RT or a control group for Year 1. For Year 2, participants chose whether to resistance train or not. Three groups emerged: train/train (n = 8: 60 ± 4 years), train/no train (n = 11: 62 ± 3 years), or controls (n = 17; 58 ± 6 years). Both training groups increased strength (p < .05) in Year 1. In Year 2, train/train maintained strength, whereas train/no train lost strength for knee extension (p < .001) but not for arm pulldown. Controls did not change. Reported physical activity levels were significantly increased in trainers in Year 1 and remained high regardless of RT in Year 2 (p < .05). Therefore, sustained changes in strength and physical activity behavior might be possible even if RT is discontinued.
Alyssa Evans, Gavin Q. Collins, Parker G. Rosquist, Noelle J. Tuttle, Steven J. Morrin, James B. Tracy, A. Jake Merrell, William F. Christensen, David T. Fullwood, Anton E. Bowden and Matthew K. Seeley
Background: Physical activity and corresponding energy expenditure can improve health in various ways. Existing methods to directly measure energy expenditure are currently limited to laboratory settings and/or expensive instrumentation. The purpose of this study was to evaluate accuracy of energy expenditure characterization, during walking and running, using demographic data, as well as data collected via an accelerometer and novel piezoresponsive foam sensors. Methods: 30 individuals (14 females; mass = 67 ± 10 kg; height = 1.74 ± 0.08 m; age = 23 ± 3 yrs) walked and ran at five speeds (1.34, 2.23, 2.68, 3.13, and 3.58 m/s) on a force-instrumented treadmill while wearing a metabolic analyzer and standardized athletic shoes instrumented with an accelerometer, and four novel nanocomposite piezoresponsive force sensors. Various predictive models, including demographic data and data derived from the accelerometer and force sensors, were evaluated for each gait speed. Results: The predictive models varied in ability to accurately characterize energy expenditure. For walking, the most accurate model included acceleration and body weight, and resulted in an average absolute error of 0.07 ± 0.03 kcal/min. For running, the most accurate model included sensor and acceleration data, and resulted in an average absolute error of 0.45 ± 0.14 kcal/min. Conclusions: When combined with acceleration data and body weight, the novel foam sensors can be used to inexpensively and accurately measure walking and running energy expenditure. This can be done at various speeds, outside of a traditional research laboratory. These results have application within a wide range of diverse contexts.
Richard J. Keegan, Lisa M. Barnett, Dean A. Dudley, Richard D. Telford, David R. Lubans, Anna S. Bryant, William M. Roberts, Philip J. Morgan, Natasha K. Schranz, Juanita R. Weissensteiner, Stewart A. Vella, Jo Salmon, Jenny Ziviani, Anthony D. Okely, Nalda Wainwright and John R. Evans
Purpose: The development of a physical literacy definition and standards framework suitable for implementation in Australia. Method: Modified Delphi methodology. Results: Consensus was established on four defining statements: Core—Physical literacy is lifelong holistic learning acquired and applied in movement and physical activity contexts; Composition—Physical literacy reflects ongoing changes integrating physical, psychological, cognitive, and social capabilities; Importance—Physical literacy is vital in helping us lead healthy and fulfilling lives through movement and physical activity; and Aspiration—A physically literate person is able to draw on his/her integrated physical, psychological, cognitive, and social capacities to support health promoting and fulfilling movement and physical activity, relative to the situation and context, throughout the lifespan. The standards framework addressed four learning domains (physical, psychological, cognitive, and social), spanning five learning configurations/levels. Conclusion: The development of a bespoke program for a new context has important implications for both existing and future programs.
Lisa M. Barnett, Dean A. Dudley, Richard D. Telford, David R. Lubans, Anna S. Bryant, William M. Roberts, Philip J. Morgan, Natasha K. Schranz, Juanita R. Weissensteiner, Stewart A. Vella, Jo Salmon, Jenny Ziviani, Anthony D. Okely, Nalda Wainwright, John R. Evans and Richard J. Keegan
Assessment of physical literacy poses a dilemma of what instrument to use. There is currently no guide regarding the suitability of common assessment approaches. The purpose of this brief communication is to provide a user’s guide for selecting physical literacy assessment instruments appropriate for use in school physical education and sport settings. Although recommendations regarding specific instruments are not provided, the guide offers information about key attributes and considerations for the use. A decision flow chart has been developed to assist teachers and affiliated school practitioners to select appropriate methods of assessing physical literacy. School physical education and sport scenarios are presented to illustrate this process. It is important that practitioners are empowered to select the most appropriate instrument/s to suit their needs.