Purpose: The behavior of an opponent has been shown to alter pacing and performance. To advance our understanding of the impact of perceptual stimuli such as an opponent on pacing and performance, this study examined the effect of a preexercise cycling protocol on exercise regulation with and without an opponent. Methods: Twelve trained cyclists performed 4 experimental, self-paced 4-km time-trial conditions on an advanced cycle ergometer in a randomized, counterbalanced order. Participants started the time trial in rested state (RS) or performed a 10-min cycling protocol at 67% peak power output (CP) before the time trial. During the time trials, participants had to ride alone (NO) or against a virtual opponent (OP). The experimental conditions were (1) RS-NO, (2) RS-OP, (3) CP-NO, and (4) CP-OP. Repeated-measures analyses of variance (P < .05) were used to examine differences in pacing and performance in terms of power output. Results: A faster pace was adopted in the first kilometer during RS-OP (318  W) compared with RS-NO (291  W; P = .03), leading to an improved finishing time during RS-OP compared with RS-NO (P = .046). No differences in either pacing or performance were found between CP-NO and CP-OP. Conclusions: The evoked response by the opponent to adopt a faster initial pace in the 4-km time trial disappeared when cyclists had to perform a preceding cycling protocol. The outcomes of this study highlight that perceived exertion alters the responsiveness to perceptual stimuli of cyclists during competition.
Marco J. Konings and Florentina J. Hettinga
Ben Langley, Nick Knight and Stewart C. Morrison
Medial tibial stress syndrome (MTSS) is a common running-related injury. Alterations in movement patterns and movement coordination patterns have been linked to the development of overuse injuries. The aim of this study was to compare transverse plane tibial and frontal plane rearfoot motion and the coordination of these movements between runners with MTSS and healthy controls. A total of 10 recreational runners with MTSS and 10 healthy controls ran at 11 km/h on a treadmill. A 3-camera motion analysis system operating at 200 Hz was used to calculate tibia and rearfoot motion. Stance phase motion patterns were compared between groups using multivariate analysis, specifically, Hotelling T 2 test with statistical parametric mapping. A modified vector coding technique was used to classify the coordination of transverse plane tibial and frontal plane rearfoot motion. The frequency of each coordination pattern displayed by each group was compared using independent samples t tests. Individuals with MTSS displayed significantly (P = .037, d = 1.00) more antiphase coordination (tibial internal rotation with rearfoot inversion) despite no significant (P > .05) differences in stance phase kinematics. The increased antiphase movement may increase the torsional stress placed upon the medial aspect of the tibia, contributing to the development of MTSS.
Ryan Zerega, Carolyn Killelea, Justin Losciale, Mallory Faherty and Timothy Sell
Rupture of the anterior cruciate ligament (ACL) remains extremely common, with over 250,000 injuries annually. Currently, clinical tests have poor utility to accurately screen for ACL injury risk in athletes. In this study, the position of a knee marker was tracked in 2-dimensional planes to predict biomechanical variables associated with ACL injury risk. Three-dimensional kinematics and ground reaction forces were collected during bilateral, single-leg stop-jump tasks for 44 healthy male military personnel. Knee marker position data were extracted to construct 2-dimensional 95% prediction ellipses in each anatomical plane. Knee marker variables included: ellipse areas, major/minor axes lengths, orientation of ellipse axes, absolute ranges of knee position, and medial knee collapse. These variables were then used as predictor variables in stepwise multiple linear regression analyses for 7 biomechanical variables associated with ACL injury risk. Knee flexion excursion, normalized peak vertical ground reaction forces, and knee flexion angle at initial contact were the response variables that generated the highest adjusted R 2 values: .71, .37, and .31, respectively. The results of this study provide initial support for the hypothesis that tracking a single marker during 2-dimensional analysis can accurately reflect the information gathered from 3-dimensional motion analysis during a task assessing knee joint stability.
Janet Lok Chun Lee and Rainbow Tin Hung Ho
In response to demographic changes in recent years, an increasing number of parks have established exercise spaces for older adults. However, limited research has been conducted to investigate how older adults utilize, experience, and perceive these spaces. This study aims to explore their experiences of using these spaces and their perspectives on these spaces by using a qualitative descriptive research design. In-depth interviews were conducted with 32 users in three Hong Kong parks with low, medium, and high area-based socioeconomic statuses. The findings highlight that exercise spaces in parks can cultivate a positive environment allowing older adults with varying physical abilities and health statuses to remain active together as well as to support each other socially and emotionally in a natural outdoor setting. The participants’ perspectives on the exercise space discussed in this study suggest that future plans for constructing such spaces in parks might benefit from a co-design approach.
Kimberly Bigelow and Michael L. Madigan
Stuart A. McErlain-Naylor
The aim of this study was to investigate student experiences of publishing undergraduate research in biomechanics. A total of 29 former students with experience of publishing peer-reviewed undergraduate biomechanics research completed an online survey regarding their perceived benefits, level of involvement, and experiences in aspects of the research process. On average, students perceived their experiences to be “largely helpful” or greater in all aspects. Areas were identified corresponding to: the greatest perceived benefits (eg, understanding of the research process); the least perceived benefits (eg, statistical analysis skills); the greatest student involvement (eg, reading relevant literature); and the least student involvement (eg, developing hypotheses and/or methods). A thematic analysis of open question responses identified themes relating to: future career, skills, scientific process, intra- and interpersonal factors, and pedagogy. Common intended learning outcomes may be achieved through involvement in the research process independently of the level of staff involvement. Staff should be encouraged to involve students in publishable biomechanics research projects where this is possible without compromising research standards and should explore ways of recreating the publishing process internally for all students.
Nicole K. Nathan, Rachel L. Sutherland, Kirsty Hope, Nicole J. McCarthy, Matthew Pettett, Ben Elton, Rebecca Jackson, Stewart G. Trost, Christophe Lecathelinais, Kathryn Reilly, John H. Wiggers, Alix Hall, Karen Gillham, Vanessa Herrmann and Luke Wolfenden
Aim: To assess the impact of a multistrategy intervention designed to improve teachers’ implementation of a school physical activity (PA) policy on student PA levels. Methods: A cluster-randomized controlled trial was conducted in 12 elementary schools. Policy implementation required schools to deliver 150 minutes of organized PA for students each week via physical education, sport, or class-based activities such as energizers. Schools received implementation support designed using the theoretical domains framework to help them implement the current policy. Results: A total of 1,502 children in kindergarten to grade 6 participated. At follow-up compared with control, students attending intervention schools had, measured via accelerometer, significantly greater increases in school day counts per minute (97.5; 95% confidence interval [CI], 64.5 to 130.4; P < .001) and moderate to vigorous physical activity (MVPA) (3.0; 95% CI, 2.2–3.8, P < .001) and a greater decrease in sedentary time (−2.1; 95% CI, −3.9 to −0.4, P = .02) per school day. Teachers in intervention schools delivered significantly more minutes (36.6 min) of PA to their students at follow-up (95% CI, 2.7–70.5, P = .04). Conclusions: Supporting teachers to implement a PA policy improves student PA. Additional strategies may be needed to support teachers to implement activities that result in larger gains in student MVPA.
Tomas Vetrovsky, Dan Omcirk, Jan Malecek, Petr Stastny, Michal Steffl and James J. Tufano
Following a 4-week control period, 24 older men and women (55–91 years) attended a 4-week progressive jumping program to determine whether assisted jumping could be safely and effectively implemented as a novel stimulus in healthy older adults. Bodyweight countermovement jump performance, isometric and isokinetic strength, postural stability, and exercise enjoyment were assessed before the control period, before the training intervention, and after the training intervention. Following the 4-week intervention, eccentric quadriceps strength increased by 19 N·m (95% confidence interval [2, 36], p = .013), bodyweight countermovement jump height increased by 1.7 cm (95% CI [0.5, 2.9], p < .001), postural sway improved by 2.1 mm/s (95% CI [0.3, 4.0], p = .026), and the participants’ perceived exercise enjoyment improved (p = .026). Therefore, using assisted jumping to induce an overspeed training stimulus in a jump training program resulted in similar performance improvements as in previous studies in older populations but with less training volume and a shorter training duration.
Danny Lum and Abdul Rashid Aziz
Force–time characteristics obtained during isometric strength tests are significantly correlated to various sporting movements. However, data on the relationship between isometric force–time characteristics and sprint kayaking performance are lacking in the literature. Purpose: The purpose of the study was, therefore, to investigate the relationship between sprint kayaking performance with ergometer performance and measures from 3 isometric strength tests: isometric squat, isometric bench press, and isometric prone bench pull. Methods: A total of 23 sprint kayaking athletes performed all 3 tests, at 90° and 120° knee angles for isometric squat and at elbow angles for isometric bench press and isometric prone bench pull, and a 200-m sprint on-water to attain the fastest time-to-completion (OWTT) possible and on a kayak ergometer to attain the highest mean power (LABTT) possible. Results: There was a significant inverse correlation between OWTT and LABTT (r = −.90, P < .001). The peak forces achieved from all isometric strength tests were significantly correlated with time-to-completion for OWTT and mean power for LABTT (r = −.44 to −.88, P < .05 and .47 to .80, P < .05, respectively). OWTT was significantly correlated with the peak rate of force development during all isometric tests except for the isometric squat at a 120° knee angle (r = −.47 to −.62, P < .05). LABTT was significantly correlated with peak rate of force development from the isometric bench press and isometric prone bench pull (r = .64–.86, P < .01). Conclusion: Based on the observed strong correlations, the mean power attained during LABTT is a good predictor of OWTT time-to-completion. Furthermore, upper- and lower-body maximum strength and peak rate of force development are equally important for on-water and ergometer sprint kayaking performance.
Alex S. Ribeiro, Ademar Avelar, Witalo Kassiano, João Pedro Nunes, Brad J. Schoenfeld, Andreo F. Aguiar, Michele C.C. Trindade, Analiza M. Silva, Luís B. Sardinha and Edilson S. Cyrino
The authors aimed to compare the effects of creatine (Cr) supplementation combined with resistance training on skeletal muscle mass (SMM), total body water, intracellular water (ICW), and extracellular water (ECW) in resistance-trained men as well as to determine whether the SMM/ICW ratio changes in response to the use of this ergogenic aid. Twenty-seven resistance-trained men received either Cr (n = 14) or placebo (n = 13) over 8 weeks. During the same period, subjects performed two split resistance training routines four times per week. SMM was estimated from appendicular lean soft tissue assessed by dual-energy X-ray absorptiometry. Total body water, ICW, and ECW were determined by spectral bioelectrical impedance. Both groups showed improvements (p < .05) in SMM, total body water, and ICW, with greater values observed for the Cr group compared with placebo. ECW increased similarly in both groups (p < .05). The SMM/ICW ratio did not change in either group (p > .05), whereas the SMM/ECW ratio decreased only in the Cr group (p < .05). A positive correlation was observed (p < .05) between SMM and ICW changes (r = .71). The authors’ results suggest that the increase in muscle mass induced by Cr combined with resistance training occurs without alteration of the ratio of ICW to SMM in resistance-trained men.