Performance in all forms of motor activity related to sport performance improves progressively during the course of the childhood years as a consequence of normal growth and development. Whether (a) sport training can accelerate and ultimately enhance this biological development and (b) the existence of certain ages when training might prove to be more effective in improving performance, particularly early in childhood, remains uncertain. Physiological adaptations to endurance training in prepubertal children (improvements in maximal oxygen uptake) are dampened compared with adults, but enhancements of strength following resistance training are equally effective at all ages. The extent that intensive training regimens characteristic of early sport specialization in children can trigger physiological and performance adaptations may therefore depend on the form of exercise involved. Clearly, additional research is needed to enhance the understanding of the physiological responses to intensive sport training in prepubertal individuals.
Thomas W. Rowland
Sandra A. Billinger, Eric D. Vidoni, Jill K. Morris, John P. Thyfault and Jeffrey M. Burns
Positive physiologic and cognitive responses to aerobic exercise have resulted in a proposed cardiorespiratory (CR) fitness hypothesis in which fitness gains drive changes leading to cognitive benefit. The purpose of this study was to directly assess the CR fitness hypothesis. Using data from an aerobic exercise trial, we examined individuals who completed cardiopulmonary and cognitive testing at baseline and 26 weeks. Change in cognitive test performance was not related to CR fitness change (r 2 = .06, p = .06). However, in the subset of individuals who gave excellent effort during exercise testing, change in cognitive test performance was related to CR fitness change (r 2 = .33, p < .01). This was largely due to change in the cognitive domain of attention (r 2 = .36, p < .01). The magnitude of change was not explained by duration of exercise. Our findings support further investigation of the CR fitness hypothesis and mechanisms by which physiologic adaptation may drive cognitive change.
Gregoire P. Millet, David J. Bentley and Veronica E. Vleck
The relationships between sport sciences and sports are complex and changeable, and it is not clear how they reciprocally influence each other. By looking at the relationship between sport sciences and the “new” (~30-year-old) sport of triathlon, together with changes in scientific fields or topics that have occurred between 1984 and 2006 (278 publications), one observes that the change in the sport itself (eg, distance of the events, wetsuit, and drafting) can influence the specific focus of investigation. The sport-scientific fraternity has successfully used triathlon as a model of prolonged strenuous competition to investigate acute physiological adaptations and trauma, as support for better understanding cross-training effects, and, more recently, as a competitive sport with specific demands and physiological features. This commentary discusses the evolution of the scientific study of triathlon and how the development of the sport has affected the nature of scientific investigation directly related to triathlon and endurance sport in general.
Bryan L. Riemann, Nancy Caggiano Tray and Scott M. Lephart
To determine the physiological adaptations that might occur with a 4-week unilateral multiaxial training program in lower leg kinesthesia, peak torque, and postural control.
True experimental pretest-posttest control-group design.
26 healthy, active subjects (14 men, 12 women).
Subjects were assigned to an experimental or control group. The experimental group performed multiaxial coordination training 3 days/wk for 4 weeks.
Main Outcome Measures:
Both groups were tested 3 times, pretest and 2 and 4 weeks after training was initiated. Outcome measures included conscious appreciation of ankle kinesthesia, eversion and dorsiflexion isokinetic peak torque, and static and functional postural control.
Results revealed a significant Group × Test interaction only for inversion kinesthesia.
Four weeks of multiaxial coordination training did not significantly improve any of the dependent variables in healthy individuals. Further research should consider the effects of such a program on injured subjects.
Jay R. Hoffman
American football is the most popular sport in the United States. Its popularity is likely related to the intense, fast-paced, physical style of play. The importance of strength and conditioning to success in football has been long understood. In fact, the strength and conditioning profession in North America can take its roots from American football. However, only recently has scientific study confirmed the positive relationships between strength, speed, and power to success in this sport. Although strength and conditioning are integral to every American football program, the collaboration with sport scientists has not been as fruitful. Only limited studies are available examining the physiological effects of actual competition and physiological adaptations or maladaptations during a season of competition. Most studies on American football have primarily focused on physical performance characteristics of these athletes and how various training paradigms can be used to improve performance.
Marianne Lacharité-Lemieux and Isabelle J. Dionne
Chronic effects of two different exercise environments on self-chosen intensity and physiological adaptations were examined in postmenopausal women. Twenty-three healthy to overweight (body mass index [BMI] 22–29 kg/m2) postmenopausal women performed three weekly training sessions during 12 weeks and were assigned to either: (1) indoor training or (2) outdoor training. Body composition, metabolic profile, and physical fitness (including Vo2max, maximal strength, and endurance) were assessed pre- and postintervention. Exercise intensity was measured every week during the training. Maximum intensity decreased significantly in time only in outdoor training (p ≤ .05). Body composition and VO2max were significantly improved indoors (p ≤ .05), whereas resting blood pressure and upper body maximal strength and endurance were improved outdoors (p ≤ .05). Indoor training is associated with maintaining intensity over time and slightly higher physiological improvements than outdoor training. However, outdoor training seems promising from a long-term perspective, due to its positive effects on health parameters and exercise adherence.
K. Anders Ericsson
Traditional theories of aging claim that basic processing speed and memory capacities show inevitable decline with increasing age. Recent research, however, has shown that older experts in some domains are able to maintain their superior performance into old age. but even they display the typical age-related decline in performance on psychometric tests of fluid intelligence. The study of expert performance shows that adults retain the capacity to acquire and maintain performance with the appropriate type of training and practice, even speeded actions and many physiological adaptations. In fact, experts’ performance keeps improving for several decades into adulthood and typically reaches its peak between 30 and 50 years of age. The experts can then maintain their attained performance level into old age by regular deliberate practice. Much of the observed decline in older adults’ performance can be attributed to age-related reductions in engagement in domain-related activities—in particular, regular deliberate practice.
Lee N. Burkett, Jack Chisum, Ralph Cook, Bob Norton, Bob Taylor, Keith Ruppert and Chris Wells
Numerous studies in the past 30 years have researched physiological adaptation to stress by wheelchair-bound subjects. Instrumentation necessary to produce this effect had to be designed and tested prior to obtaining valid data. This study had two main purposes: to design a wheelchair ergometer for physiological testing of spinal cord-injured subjects, and to demonstrate the validity of the maximal stress test when using the wheelchair ergometer. To test the validity of the wheelchair ergometer, 10 disabled subjects (9 paraplegic and 1 quadriplegic) participated in both a maximal field test (FT) and a maximal wheelchair ergometer test (WERG), with each subject serving as his or her own control. A randomly assigned counterbalanced design (5 subjects assigned to complete the FT first, with the second group of 5 subjects completing the WERG first) was used to reduce the learning effect in the study. The results of the t-tests indicated there was no significant difference between V̇O2 and V̇E, (STPD) averages for the WERG and FT for maximal effort with two-tailed significant levels of t = .9016 and t = .7294, respectively. The Pearson product moment correlation level was statistically significant at p < .0001, when the WERG V̇O2 was compared to the FT V̇O2 (r = .94), and was significant at p < .005 when the WERG V̇E was compared to the FT V̇E (r = .82).
Scott C. Forbes, Nathan Sletten, Cody Durrer, Étienne Myette-Côté, D. Candow and Jonathan P. Little
High-intensity interval training (HIIT) has been shown to improve cardiorespiratory fitness, performance, body composition, and insulin sensitivity. Creatine (Cr) supplementation may augment responses to HIIT, leading to even greater physiological adaptations. The purpose of this study was to determine the effects of 4 weeks of HIIT (three sessions/week) combined with Cr supplementation in recreationally active females. Seventeen females (age = 23 ± 4 yrs; BMI = 23.4 ± 2.4) were randomly assigned to either Cr (Cr; 0.3 g・kg-1・d-1 for 5 d followed by 0.1 g・kg-1・d-1 for 23 days; n = 9) or placebo (PLA; n = 8). Before and after the intervention, VO2peak, ventilatory threshold (VT), time-trial performance, lean body mass and fat mass, and insulin sensitivity were assessed. HIIT improved VO2peak (Cr = +10.2%; PLA = +8.8%), VT (Cr = +12.7%; PLA = +9.9%), and time-trial performance (Cr = -11.5%; PLA = -11.6%) with no differences between groups (time main effects, all p < .001). There were no changes over time for fat mass (Cr = -0.3%; PLA = +4.3%), whole-body lean mass (Cr = +0.5%; PLA = -0.9%), or insulin resistance (Cr = +3.9%; PLA = +18.7%). In conclusion, HIIT is an effective way to improve cardiorespiratory fitness, VT, and time-trial performance. The addition of Cr to HIIT did not augment improvements in cardiorespiratory fitness, performance or body composition in recreationally active females.
Laura A. Garvican, Kristal Hammond, Matthew C. Varley, Christopher J. Gore, Francois Billaut and Robert J. Aughey
This study investigated the decrement in running performance of elite soccer players competing at low altitude and time course for abatement of these decrements.
Twenty elite youth soccer players had their activity profile, in a sea-level (SL) and 2 altitude (Alt, 1600 m, d 4, and d 6) matches, measured with a global positioning system. Measures expressed in meters per minute of match time were total distance, low- and high-velocity running (LoVR, 0.01–4.16 m/s; HiVR, 4.17–10.0 m/s), and frequency of maximal accelerations (>2.78 m/s2). The peak and subsequent stanza for each measure were identified and a transient fatigue index calculated. Mean heart rate (HR) during the final minute of a submaximal running task (5 min, 11 km/h) was recorded at SL and for 10 d at Alt. Differences were determined between SL and Alt using percentage change and effect-size (ES) statistic with 90% confidence intervals.
Mean HR almost certainly increased on d 1 (5.4%, ES 1.01 ± 0.35) and remained probably elevated on both d 2 (ES 0.42 ± 0.31) and d3 (ES 0.30 ± 0.25), returning to baseline at d 5. Total distance was almost certainly lower than SL (ES –0.76 ± 0.37) at d 4 and remained probably reduced on d 6 (ES –0.42 ± 0.36). HiVR probably decreased at d 4 vs SL (–0.47 ± 0.59), with no clear effect of altitude at d 6 (–0.08 ± 0.41). Transient fatigue in matches was evident at SL and Alt, with a possibly greater decrement at Alt.
Despite some physiological adaptation, match running performance of youth soccer players is compromised for at least 6 d at low altitude.