Purpose: To analyze the energetic profiles of the Yo-Yo Intermittent Recovery Tests 1 and 2 (YYIR1 and YYIR2). Methods: Intermittent running distance (IR1D and IR2D), time to exhaustion (IR1T and IR2T), and total recovery time between shuttles (IR1R and IR2R) were measured in 10 well-trained male athletes (age 24.4 [2.0] y, height 182  cm, weight 75.8 [7.9] kg). Respiratory gases and blood lactate (BLC) were obtained preexercise, during exercise, and until 15 min postexercise. Metabolic energy, average metabolic power , and energy share (percentage of aerobic [W AER], anaerobic lactic [W BLC], and anaerobic alactic energy system [W PCr]) were calculated using the PCr-La-O2 method. Results: Peak oxygen consumption was possibly higher in YYIR2 (60.3 [5.1] mL·kg−1·min−1) than in YYIR1 (P = .116, 57.7 [4.5] mL·kg−1·min−1, d = −0.58). IR1D, IR1T, and IR1R were very likely higher than IR2D, IR2T, and IR2R, respectively (P < .001, 1876  vs 672  m, d = −2.83; P < .001, 916  vs 304  s, d = −3.03; and P < .001, 460  vs 150  s, d = −2.83). Metabolic energy was most likely lower in YYIR2 than in YYIR1 (P < .001, 493.5 [118.1] vs 984.8 [171.7] kJ, d = 3.24). Average metabolic power was most likely higher in YYIR2 than in YYIR1 (P < .001, 21.5 [1.7] vs 14.5 [2.2] W·kg−1, d = 3.54). When considering aerobic phosphocreatine restoration during breaks between shuttles, W AER (P = .693, 49% [10%] vs 48% [5%], d = −0.16) was similar, W PCr (P = .165, 47% [11%] vs 42% [6%], d = −0.54) possibly higher, and W BLC (P < .001, 4% [1%] vs 10% [3%], d = 1.95) almost certainly lower in YYIR1 than in YYIR2. Conclusions: W AER and W PCr are predominant in YYIR1 and YYIR2 with almost identical W AER. Higher IR1D and IR1T in YYIR1 result in higher metabolic energy but lower average metabolic power and slightly lower peak oxygen consumption. Higher IR1R allows for higher reliance on W PCr in YYIR1, while YYIR2 requires a higher fraction of W BLC.
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Sebastian Kaufmann, Olaf Hoos, Timo Kuehl, Thomas Tietz, Dominik Reim, Kai Fehske, Richard Latzel and Ralph Beneke
Stephen Harvey and Jeffrey P. Carpenter
Purpose: This descriptive study investigates the genesis and change in physical educators’ social media use for professional development and learning. Method: Data were collected through semistructured interviews with 48 physical educators who had actively used various social media professionally for an extended period of time. The data were analyzed inductively and aligned to the basic psychological needs defined by self-determination theory: relatedness, autonomy, and competence. Results: Building relationships with a trusted network of people and opportunities to express their autonomy were important drivers in the participants’ genesis and continued use of social media. Developing competence at both the start and throughout their social media journey was also critical. Discussion/Conclusions: The findings provide a starting point for in-depth research on the motivational characteristics underpinning physical educators’ reasons for starting and continuing to use social media for professional development and learning, and how these might change over time based on different psychological needs.
Nuria Romero-Parra, Victor Manuel Alfaro-Magallanes, Beatriz Rael, Rocío Cupeiro, Miguel A. Rojo-Tirado, Pedro J. Benito, Ana B. Peinado and on behalf of the IronFEMME Study Group
Context: The indirect markers of muscle damage have been previously studied in females. However, inconclusive results have been found, possibly explained by the heterogeneity regarding monitoring and verification of menstrual-cycle phase. Purpose: To determine whether the fluctuations in sex hormones during the menstrual cycle influence muscle damage. Methods: A total of 19 well-trained eumenorrheic women (age 28.6 [5.9] y; height 163.4 [6.1] cm; weight 59.6 [5.8] kg body mass) performed an eccentric-based resistance protocol consisting of 10 × 10 back squats at 60% of their 1-repetition maximum on the early follicular phase (EFP), late follicular phase, and midluteal phase of the menstrual cycle. Range of motion, muscle soreness, countermovement jump, and limb circumferences were evaluated prior to 24 and 48 hours postexercise. Perceived exertion was evaluated after each set. Results: Differences in sex hormones indicated that tests were adequately performed in the different menstrual-cycle phases. Prior to exercise, muscle soreness was higher in the EFP (4.7 [7.7]) than in the late follicular phase (1.1 [3.2]; P = .045). No other variables showed significant differences between phases. Time-point differences (baseline, 24, and 48 h) were observed in knee range of motion (P = .02), muscle soreness, countermovement jump, and between sets for perceived exertion (P < .001). Conclusion: Although the protocol elicited muscle damage, hormonal fluctuations over the menstrual cycle did not seem to affect indirect markers of muscle damage, except for perceived muscle soreness. Muscle soreness was perceived to be more severe before exercise performed in EFP, when estrogen concentrations are relatively low. This may impair women’s predisposition to perform strenuous exercise during EFP.
Robert J. Gregor
Prasanna Sritharan, Luke G. Perraton, Mario A. Munoz, Peter Pivonka and Adam L. Bryant
This study compared lower-limb muscle function, defined as the contributions of muscles to center-of-mass support and braking, during a single-leg hopping task in anterior cruciate ligament-reconstructed (ACLR) individuals and uninjured controls. In total, 65 ACLR individuals and 32 controls underwent a standardized anticipated single-leg forward hop. Kinematics and ground reaction force data were input into musculoskeletal models to calculate muscle forces and to quantify muscle function by decomposing the vertical (support) and fore-aft (braking) ground reaction force components into contributions by individual lower-limb muscles. Four major muscles, the vasti, soleus, gluteus medius, and gluteus maximus, were primarily involved in support and braking in both ACLR and uninjured groups. However, although the ACLR group demonstrated lower peak forces for these muscles (all Ps < .001, except gluteus maximus, P = .767), magnitude differences in these muscles’ contributions to support and braking were not significant. ACLR individuals demonstrated higher erector spinae (P = .012) and hamstrings forces (P = .085) to maintain a straighter, stiffer landing posture with more forward lumbar flexion. This altered landing posture may have enabled the ACLR group to achieve similar muscle function to controls, despite muscle force deficits. Our findings may benefit rehabilitation and the development of interventions to enable faster and safer return to sport.
Alison Schinkel-Ivy, Vicki Komisar and Carolyn A. Duncan
Investigating balance reactions following continuous, multidirectional, support surface perturbations is essential for improving our understanding of balance control in moving environments. Segmental motions are often incorporated into rapid balance reactions following external perturbations to balance, although the effects of these motions during complex, continuous perturbations have not been assessed. This study aimed to quantify the contributions of body segments (ie, trunk, head, upper extremity, and lower extremity) to the control of center-of-mass (COM) movement during continuous, multidirectional, support surface perturbations. Three-dimensional, whole-body kinematics were captured while 10 participants experienced 5 minutes of perturbations. Anteroposterior, mediolateral, and vertical COM position and velocity were calculated using a full-body model and 7 models with reduced numbers of segments, which were compared with the full-body model. With removal of body segments, errors relative to the full-body model increased, while relationship strength decreased. The inclusion of body segments appeared to affect COM measures, particularly COM velocity. Findings suggest that the body segments may provide a means of improving the control of COM motion, primarily its velocity, during continuous, multidirectional perturbations, and constitute a step toward improving our understanding of how the limbs contribute to balance control in moving environments.
Mhairi J. MacDonald, Samantha G. Fawkner and Ailsa G. Niven
Background: In order to promote walking, researchers have sought to identify the required step rate to maintain a health-enhancing walking intensity However, there is limited evidence regarding the stepping rate required to promote moderate-intensity walking in adolescent girls. Purpose: To identify the step rate equivalent to moderate-intensity physical activity (MPA) in adolescent girls and to explore the influence that different anthropometric measures may have on the step rate equating to MPA in this population. Methods: A total of 56 adolescent girls (mean age = 13.8[0.7] y) were recruited to the study. Anthropometric variables and resting metabolic rate were assessed, followed by 3 overground walking trials on a flat surface at approximately 2, 3, and 4 mph, each lasting a minimum of 4 minutes. Oxygen uptake was assessed using a portable gas analyzer and subsequently converted into metabolic equivalents (METs). Step count was assessed by real-time direct observation hand tally. Results: Employing the linear regression between step rate and METs (r 2 = .20, standard error of estimates = 0.003) suggests that 120 steps per minute was representative of an MPA (3 METs) equating to 7200 steps in 60 minutes. Multiple regression and mixed-model regression confirmed weight-related variables and maturity were significant predictors of METs (P < .01). Conclusion: The results suggest that, at population level, a step rate of 120 steps per minute may be advocated to achieve MPA in adolescent girls; although, due to the small sample size used, caution should be applied. At an individual level, other factors, such as age and weight, should be considered.
Alejandra Jáuregui, Selene Pacheco-Miranda, Armando García-Olvera and Emanuel Orozco-Núñez
Background: Quality physical education (QPE) is part of a whole-of-school approach for school-based physical activity promotion. The United Nations Educational, Scientific and Cultural Organization QPE Policy Project supported 4 countries to develop QPE policies. The authors summarize the process, progress, successes, setbacks, and lessons learned during the implementation of the project in Mexico. Methods: The project was developed from August 2016 to April 2018 following the methodology proposed by the United Nations Educational, Scientific and Cultural Organization. Adaptations to the methodology were made to meet local needs. Results and Discussion: The project successfully implemented the United Nations Educational, Scientific and Cultural Organization methodology and prepared a national strategy for the provision of QPE in Mexico. The national strategy progressed despite the change in presidential administration. Successes included the use of a QPE policy evaluation framework, the inclusion of stakeholders representing extreme PE views and from all regions in the country, and the presence of international agencies in the national team. Setbacks included difficulties in engaging key organizations and a weak communication campaign. Lessons learned are discussed. Conclusions: The QPE project in Mexico served as a pilot project to test the feasibility of implementing a QPE policy revision process. The experience and lessons learned in Mexico can be drawn on to inform the work of other stakeholders interested in advocating for a national QPE policy.
Christopher C. Moore, Aston K. McCullough, Elroy J. Aguiar, Scott W. Ducharme and Catrine Tudor-Locke
Background: The authors conducted a scoping review as a first step toward establishing harmonized (ie, consistent and compatible), empirically based best practices for validating step-counting wearable technologies. Purpose: To catalog studies validating step-counting wearable technologies during treadmill ambulation. Methods: The authors searched PubMed and SPORTDiscus in August 2019 to identify treadmill-based validation studies that employed the criterion of directly observed (including video recorded) steps and cataloged study sample characteristics, protocol details, and analytical procedures. Where reported, speed- and wear location–specific mean absolute percentage error (MAPE) values were tabulated. Weighted median MAPE values were calculated by wear location and a 0.2-m/s speed increment. Results: Seventy-seven eligible studies were identified: most had samples averaging 54% (SD = 5%) female and 27 (5) years of age, treadmill protocols consisting of 3 to 5 bouts at speeds of 0.8 (0.1) to 1.6 (0.2) m/s, and reported measures of bias. Eleven studies provided MAPE values at treadmill speeds of 1.1 to 1.8 m/s; their weighted median MAPE values were 7% to 11% for wrist-worn, 1% to 4% for waist-worn, and ≤1% for thigh-worn devices. Conclusions: Despite divergent study methodologies, the authors identified common practices and summarized MAPE values representing device step-count accuracy during treadmill walking. These initial empirical findings should be further refined to ultimately establish harmonized best practices for validating wearable technologies.
Robert Turick, Anthony Weems, Nicholas Swim, Trevor Bopp and John N. Singer
One prominent, well-debated issue in the American higher education system is whether university officials should remove the names of individuals with racist pasts from campus buildings/structures that bear their namesake. The purpose of this study was to analyze basketball and football facilities at Division I Football Bowl Subdivision institutions to explore the racialized history of the people whom these facilities are named after. Utilizing a collective case study approach, the authors identified 18 facilities that were named after athletic administrators, coaches, and philanthropists who engaged in racist activities or harbored racist views. The authors argue, using critical race theory and systemic racism theory as interpretative lenses, that naming buildings after racist persons legitimizes their legacies, rationalizes systemic racism, and continues to unjustly enrich this particular group.