Shawn C. Sorenson

Knee Extensor Dynamics in the Volleyball Approach Jump: The Influence of Patellar Tendinopathy

STUDY DESIGN Controlled laboratory study using a cross-sectional design. OBJECTIVES To evaluate knee joint dynamics in elite volleyball players with and without a history of patellar tendinopathy, focusing on mechanical energy absorption and generation. We hypothesized that tendinopathy would be associated withreduced net joint work and net joint power. BACKGROUND Patellar tendinopathy is a common, debilitating injury affecting competitive volleyball players. METHODS Thirteen elite male players with and without a history of patellar tendinopathy (mean ± SD age, 27 ± 7 years) performed maximum-effort volleyball approach jumps. Sagittal plane knee joint kinematics, kinetics, and energetics were quantified in the lead limb, using data obtained from a force platform and an 8-camera motion analysis system. Vertical ground reaction forces and pelvis vertical velocity at takeoff were examined. Independent sample t tests were used to evaluate group differences (α = .05). RESULTS The tendinopathy group, compared to controls, demonstrated significant reductions (approximately 30%) in net joint work and net joint power during the eccentric phase of the jump, with no differences in the concentric phase. Positive to-negative net joint work and net joint power ratios were significantly higher in the tendinopathy group, which had a net joint work ratio of 1.00 (95% CI: 0.77, 1.24) versus 0.76 (95% CI: 0.64, 0.88) for controls, and a net joint power ratio of 1.62 (95% CI: 1.15, 2.10) versus 1.00 (95% CI: 0.80, 1.21) for controls. There were no significant differences in net joint moment, angular velocity, or range of motion. Peak vertical ground reaction forces were lower for the tendinopathy group, while average vertical ground reaction forces and pelvis vertical velocity were similar. CONCLUSION Patellar tendinopathy is associated with differences in sagittal plane mechanical energy absorption at the knee during maximum-effort volleyball approach jumps. Net joint work and net joint power may help define underlying mechanisms, adaptive effects, or rehabilitative strategies for individuals with patellar tendinopathy.

Life span exercise among elite intercollegiate student athletes.

Background: Despite prominent public attention, data on life span health and exercise outcomes among elite, competitive athletes are sparse and do not reflect the diversity of modern athletes. Hypothesis: Life span exercise behavior differs between National Collegiate Athletic Association (NCAA) student athletes and a nonathlete control group. Sustained exercise is associated with improved cardiopulmonary health outcomes. Study Design: Cross-sectional, descriptive epidemiology study. Level of Evidence: Level 3. Methods: A total of 496 students and alumni (age range, 17-84 year) at a large, NCAA Division I university, including student athletes and an age- and sex-matched nonathlete control group, completed anonymous, self-report health and exercise questionnaires. Age-stratified, cross-sectional analysis evaluated previous week’s total exercise volume (ExVol), self-rated exercise importance (ExImp), and compliance with American College of Sports Medicine (ACSM) exercise guidelines for healthy adults. The association of ACSM guideline compliance with lifetime cardiopulmonary health outcomes was also assessed. Results: Current student athletes reported significantly greater ExVol (P < 0.001. Cohen d = 0.99, probability of clinically important difference [pCID] >99.5%), ExImp (P < 0.001, d = 1.96, pCID = 96%), and likelihood of compliance with ACSM guidelines (odds ratio [OR], 95% confidence interval [CI] = 30.6, 11.0-84.6) compared with nonathletes. No significant differences were found between alumni student athletes and nonathletes. Alumni student athletes demonstrated substantially lower ExVol (P < 0.001, d = –0.94, pCID >99.5%) and guideline compliance (OR = 0.09, 95% CI = 0.05-0.19) compared with current student athletes, whereas nonathletes had similar exercise behavior across the life span. Among alumni, ACSM guideline compliance was associated with significant attenuation of cardiopulmonary health concerns (P = 0.02, d = –0.50, pCID = 14%) independent of intercollegiate athletic participation. Conclusion: Although current NCAA Division I student athletes demonstrated significant, clinically important differences in exercise behavior compared with nonathletes, no group differences were evident later in life. Irrespective of collegiate athletic status, healthy exercise behavior among alumni was associated with cardiopulmonary health benefits. Clinical Relevance: To realize life span health benefits, it is imperative that student athletes maintain consistent patterns of healthy exercise beyond retirement from competitive sports.

Holistic Life-Span Health Outcomes Among Elite Intercollegiate Student-Athletes

CONTEXT Competitive sports are recognized as having unique health benefits and risks, and the effect of sports on life-span health among elite athletes has received increasing attention. However, supporting scientific data are sparse and do not represent modern athletes. OBJECTIVE To assess holistic life-span health and health-related quality-of-life (HRQL) among current and former National Collegiate Athletic Association student-athletes (SAs). DESIGN Cross-sectional study. SETTING A large Division I university. PATIENTS OR OTHER PARTICIPANTS Population-based sample of 496 university students and alumni (age 17-84 years), including SAs and an age-matched and sex-matched nonathlete (NA) control group. MAIN OUTCOME MEASURE(S) Participants completed anonymous, self-report questionnaires. We measured the Short-Form 12 (SF-12) physical and mental component HRQL scores and cumulative lifetime experience and relative risk of treatment for joint, cardiopulmonary, and psychosocial health concerns. RESULTS Older alumni (age 43+ years) SAs reported greater joint health concerns than NAs (larger joint summary scores; P = .04; Cohen d = 0.69; probability of clinically important difference [pCID] = 77%; treatment odds ratio [OR] = 14.0, 95% confidence interval [CI] = 1.6, 126). Joint health for current and younger alumni SAs was similar to that for NAs. Older alumni reported greater cardiopulmonary health concerns than younger alumni (summary score P < .001; d = 1.05; pCID = 85%; OR = 5.8, 95% CI = 2.0, 16) and current students (P < .001; d = 2.25; pCID >99.5%; OR = 7.1, 95% CI = 3.3, 15), but the risk was similar for SAs and NAs. Current SAs demonstrated evidence of better psychosocial health (summary score P = .006; d = -0.52; pCID = 40%) and mental component HRQL (P = .008; d = 0.50; pCID = 48%) versus NAs but similar psychosocial treatment odds (OR = 0.87, 95% CI = 0.39, 1.9). Psychosocial health and mental component HRQL were similar between alumni SAs and NAs. No differences were observed between SAs and NAs in physical component HRQL. CONCLUSIONS The SAs demonstrated significant, clinically meaningful evidence of greater joint health concerns later in life, comparable cardiopulmonary health, and differences in life-span psychosocial health and HRQL profiles compared with NAs. These data provide timely evidence regarding a compelling public issue and highlight the need for further study of life-span health among modern athletes.

The Trojan Lifetime Champions Health Survey: Development, Validity, and Reliability

CONTEXT Self-report questionnaires are an important method of evaluating lifespan health, exercise, and health-related quality of life (HRQL) outcomes among elite, competitive athletes. Few instruments, however, have undergone formal characterization of their psychometric properties within this population. OBJECTIVE To evaluate the validity and reliability of a novel health and exercise questionnaire, the Trojan Lifetime Champions (TLC) Health Survey. DESIGN Descriptive laboratory study. SETTING A large National Collegiate Athletic Association Division I university. PATIENTS OR OTHER PARTICIPANTS A total of 63 university alumni (age range, 24 to 84 years), including former varsity collegiate athletes and a control group of nonathletes. INTERVENTION(S) Participants completed the TLC Health Survey twice at a mean interval of 23 days with randomization to the paper or electronic version of the instrument. MAIN OUTCOME MEASURE(S) Content validity, feasibility of administration, test-retest reliability, parallel-form reliability between paper and electronic forms, and estimates of systematic and typical error versus differences of clinical interest were assessed across a broad range of health, exercise, and HRQL measures. RESULTS Correlation coefficients, including intraclass correlation coefficients (ICCs) for continuous variables and κ agreement statistics for ordinal variables, for test-retest reliability averaged 0.86, 0.90, 0.80, and 0.74 for HRQL, lifetime health, recent health, and exercise variables, respectively. Correlation coefficients, again ICCs and κ, for parallel-form reliability (ie, equivalence) between paper and electronic versions averaged 0.90, 0.85, 0.85, and 0.81 for HRQL, lifetime health, recent health, and exercise variables, respectively. Typical measurement error was less than the a priori thresholds of clinical interest, and we found minimal evidence of systematic test-retest error. We found strong evidence of content validity, convergent construct validity with the Short-Form 12 Version 2 HRQL instrument, and feasibility of administration in an elite, competitive athletic population. CONCLUSIONS These data suggest that the TLC Health Survey is a valid and reliable instrument for assessing lifetime and recent health, exercise, and HRQL, among elite competitive athletes. Generalizability of the instrument may be enhanced by additional, larger-scale studies in diverse populations.

Misleading Interpretations and Public Misinformation on Human Growth Hormone in Athletes

The article by Meinhardt and colleagues (1) isimportant and informative. This randomized, controlled trial evalu-ating the independent and synergistic effects of exogenous growthhormone and testosterone on selected physiologic and athletic per-formance measures is a valuable contribution to the scientific litera-ture. It also provides critical evidence to the ongoing social andscientific debate surrounding sports doping.The study shows significant increases in anaerobic work capac-ity, as measured by the Wingate cycle test, after 8 weeks of treatmentwith growth hormone, with and without concurrent testosteroneadministration. Although effect sizes were modest (0.22 to 0.38 forgrowth hormone alone and 0.61 for growth hormone and testoster-one), these findings suggest a previously unreported physiologic ef-fect that has potential implications for athletic performance. Theauthors correctly conclude, however, that the athletic significance ofthese findings is uncertain.Unfortunately, oversights in the presentation of this importantwork have led to erroneous interpretations in the mainstream mediathat compromise its effect and carry dangerous ramifications, espe-cially when viewed by an untrained audience.The characterization of anaerobic work capacity as “sprint ca-pacity” is inaccurate and misleading. Although equivocal supportexists for cycle ergometry as a significant predictor of sprinting per-formance (2, 3), it is widely recognized that additional factors, in-cluding strength and power, are important determinants (4, 5). Tosuggest even semantically that Wingate test performance and sprintcapacity are equivalent measures is wrong.More egregiously, even while acknowledging such limitations,the authors go on to speculate in specific terms how their findings inrecreational athletes translate to 100-meter running times and 50-meter swimming times in world-class competitors: “We do not knowhow an improvement in Wingate test performance translates to per-formance in the sporting field, but we speculate that the approxi-mately 4% increase in sprint capacity that we observed could trans-late to an improvement of 0.4 second in a 10-second sprint over 100meters or of 1.2 seconds in a 30-second swim over 50 meters.” Thisclaim is made without basis, evidence, or even a compelling expla-nation. Nonetheless, it forms the featured conclusion of numerousprominent media reports, including this from the

Age-related changes to composite lower extremity kinetics and their constituents in healthy gait: A perspective on contributing factors and mechanisms

Abstract This perspective examines the isolated effect of healthy aging on combined lower extremity and individual joint kinetics during gait, as well as mechanisms for this adaptation. Older adults redistribute neuromuscular effort from the ankle to the hip without changes in overall lower extremity kinetics. This kinetic effect parallels kinematic alterations to stride characteristics and body segment geometry. Evidence suggests that both kinetic and kinematic factors may drive observed adaptations with aging. There is stronger support for the influence of kinematic effects, including increased hip flexion, body center of mass repositioning, and balance‐driven control strategies. These data indicate that appropriate interventions may alter age‐related changes. Further, insights gained from the study of healthy aging may be applied to better understand the independent effects of other adaptive stimuli such as degeneration, acute injury, or exercise. Finally, this analysis demonstrates that due consideration of task sensitivity, kinematic/kinetic interdependence, and conscious/unconscious motor control is critical to any biomechanical investigation of an aging population.