Browse

You are looking at 141 - 150 of 16,934 items for :

  • Sport and Exercise Science/Kinesiology x
  • All content x
Clear All
Restricted access

Michael A. Hunt, Christopher K. Cochrane, Andrew M. Schmidt, Honglin Zhang, David J. Stockton, Alec H. Black, and David R. Wilson

Knee osteoarthritis is thought to result, in part, from excessive and unbalanced joint loading. Toe-in and toe-out gait modifications produce alterations in external knee joint moments, and some improvements in pain over the short- and long-term. The aim of this study was to probe mechanisms of altered joint loading through the assessment of tibiofemoral contact in standing with toe-in and toe-out positions using an open magnetic resonance scanner. In this study, 15 young, healthy participants underwent standing magnetic resonance imaging of one of their knees in 3 foot positions. Images were analyzed to determine contact in the tibiofemoral joint, with primary outcomes including centroid of contact and contact area for each compartment and overall. The centroid of contact shifted laterally in the lateral compartment with both toe-in and toe-out postures, compared with the neutral position (P < .01), while contact area in the medial and lateral compartments showed no statistical differences. Findings from this study indicate that changes in the loading anatomy are present in the tibiofemoral joint with toe-in and toe-out and that a small amount of lateralization of contact, especially in the lateral compartment, does occur with these altered lower limb orientations.

Restricted access

Daniel J. Davis and John H. Challis

Time-differentiating kinematic signals from optical motion capture amplifies the inherent noise content of those signals. Commonly, biomechanists address this problem by applying a Butterworth filter with the same cutoff frequency to all noisy displacement signals prior to differentiation. Nonstationary signals, those with time-varying frequency content, are widespread in biomechanics (eg, those containing an impact) and may necessitate a different filtering approach. A recently introduced signal filtering approach wherein signals are divided into sections based on their energy content and then Butterworth filtered with section-specific cutoff frequencies improved second derivative estimates in a nonstationary kinematic signal. Utilizing this signal-section filtering approach for estimating running vertical ground reaction forces saw more of the signal’s high-frequency content surrounding heel strike maintained without allowing inappropriate amounts of noise contamination in the remainder of the signal. Thus, this signal-section filtering approach resulted in superior estimates of vertical ground reaction forces compared with approaches that either used the same filter cutoff frequency across the entirety of each signal or across the entirety of all signals. Filtering kinematic signals using this signal-section filtering approach is useful in processing data from tasks containing an impact when accurate signal second derivative estimation is of interest.

Restricted access

Chungyi Chiu, Alicia R. Covello-Jones, Esteban Montenegro, Jessica M. Brooks, and Sa Shen

Background: Physical activity benefits have been extensively studied. However, the public health guidelines seem unclear about the relationships between steps and movements with healthy biomarkers for people with (PWD) and without disabilities (PWOD), respectively. While public health guidelines illustrate types of exercise (eg, running, swimming), it is equally important to provide data-driven recommended amounts of daily steps or movements to achieve health biomarkers and further promote a physically active lifestyle. Methods: Data from the National Health and Nutrition Examination Survey 2003–2006 were used. The authors conducted sensitivity, specificity, and receiver-operating-characteristic curve analyses regarding cut points from ActiGraph 7164 of daily steps and movements for health biomarkers (eg, body mass index, cholesterol) in PWD (2178 participants) and PWOD (4414 participants). The authors also examined the dose relationships of steps, movements, and healthy biomarkers in each group. Results: The authors found significant differences in the cut points of daily steps and movement for health biomarkers in PWD and PWOD. For daily steps, cut points of PWD were ranged from 3222 to 8311 (area under the receiver-operating-characteristic curve [AUC] range = 0.52–0.93) significantly lower than PWOD’s daily steps (range = 5455–14,272; AUC = 0.58–0.87). For daily movement, cut points of PWD were ranged from 115,451 to 430,324 (AUC = 0.53–0.91) significantly lower than the PWOD’s daily movements (range = 215,288–282,307; AUC = 0.60–0.88). The authors found strong but different dose relationships of many biomarkers in each group. Conclusions: PWD need fewer daily steps or movement counts to achieve health biomarkers than PWOD. The authors provided data-driven, condition-specific recommendations on promoting a physically active lifestyle.

Full access

Annegret Schlund, Anne K. Reimers, Jens Bucksch, Catherina Brindley, Carolin Schulze, Lorri Puil, Stephanie E. Coen, Susan P. Phillips, Guido Knapp, and Yolanda Demetriou

Background: Physical inactivity is often reported in youth and differs among boys and girls. The aim of this study is to assess sex/gender considerations in intervention studies promoting physical activity and reducing sedentary behavior in youth using a sex/gender checklist. Methods: A systematic search was conducted in August 2018 to identify all relevant controlled trials. Studies screened must have reported a quantified measure of physical activity and/or sedentary behavior, and identified participants by sex/gender at baseline. For evaluation of the sex/gender consideration, the authors used a sex/gender checklist developed by expert consensus. Results: The authors reviewed sex/gender considerations in all aspects of intervention development, implementation, and evaluation in 217 studies. Sex/gender aspects were only rudimentarily taken into account, most frequently during statistical analyses, such as stratification or interaction analysis. Conclusions: Sex/gender effects are not sufficiently reported. To develop guidelines that are more inclusive of all girls and boys, future interventions need to document sex/gender differences and similarities, and explore whether sex/gender influences different phases of intervention programs. The newly developed sex/gender checklist can hereby be used as a tool and guidance to adequately consider sex/gender in the several steps of intervention planning, implementation, and evaluation.

Restricted access

Ryo Yamanaka, Shinya Wakasawa, Koya Yamashiro, Naoki Kodama, and Daisuke Sato

Purpose: The study determined whether the increase in the cross-sectional area (CSA) of psoas major, which is known as a hip-flexion muscle, by resistance training combined with running training improves the performance of long-distance runners. Methods: Subjects were 8 well-trained male long-distance runners. The personal best time in a 5000-m race was 15:10.0 (0:20.5) (mean [SD]). Each subject performed resistance training twice per week with running training for 12 weeks. The authors used 3 resistance training regimens that would train the hip flexor muscles. Training intensity was a maximum of 10 repetitions. The training amount was 3 sets × 10 times during the first 4 weeks followed by 4 sets × 10 times during the last 8 weeks. The authors measured the CSA of psoas major using magnetic resonance imaging and the performance of long-distance runners using a constant velocity running test before (pre) and after (post) the training term. Results: The combination training significantly (P < .01, d = 0.34) increased the CSA of psoas major (pre: 16.2 [1.5] cm2, post: 16.7 [1.4] cm2) and significantly (P < .01, d = 1.41) improved the duration of the constant velocity running test (pre: 500 [108] s, post: 715 [186] s). Moreover, multiple regression analysis showed that the pre to post change in the duration of the constant velocity exercise was significantly correlated with the change in CSA of the psoas major. Conclusion: The authors suggest that resistance training of psoas major with running training is correlated with an improvement in the performance of long-distance runners.

Restricted access

Sebastien Racinais, Julien D. Périard, Julien Piscione, Pitre C. Bourdon, Scott Cocking, Mohammed Ihsan, Mathieu Lacome, David Nichols, Nathan Townsend, Gavin Travers, Mathew G. Wilson, and Olivier Girard

Purpose: To investigate whether including heat and altitude exposures during an elite team-sport training camp induces similar or greater performance benefits. Methods: The study assessed 56 elite male rugby players for maximal oxygen uptake, repeated-sprint cycling, and Yo-Yo intermittent recovery level 2 (Yo-Yo) before and after a 2-week training camp, which included 5 endurance and 5 repeated-sprint cycling sessions in addition to daily rugby training. Players were separated into 4 groups: (1) control (all sessions in temperate conditions at sea level), (2) heat training (endurance sessions in the heat), (3) altitude (repeated-sprint sessions and sleeping in hypoxia), and (4) combined heat and altitude (endurance in the heat, repeated sprints, and sleeping in hypoxia). Results: Training increased maximal oxygen uptake (4% [10%], P = .017), maximal aerobic power (9% [8%], P < .001), and repeated-sprint peak (5% [10%], P = .004) and average power (12% [14%], P < .001) independent of training conditions. Yo-Yo distance increased (16% [17%], P < .001) but not in the altitude group (P = .562). Training in heat lowered core temperature and increased sweat rate during a heat-response test (P < .05). Conclusion: A 2-week intensified training camp improved maximal oxygen uptake, repeated-sprint ability, and aerobic performance in elite rugby players. Adding heat and/or altitude did not further enhance physical performance, and altitude appears to have been detrimental to improving Yo-Yo.

Restricted access

Patricia Rehder-Santos, Raphael M. Abreu, Étore De F. Signini, Claudio D. da Silva, Camila A. Sakaguchi, Carla C. Dato, and Aparecida M. Catai

Background and Objective: Inspiratory muscle training (IMT) produced outstanding results in the physical performance of active subjects; however, little is known about the best training intensity for this population. The objective was to investigate the impact of an IMT of high intensity, using the critical inspiratory pressure (CIP), on inspiratory muscle strength (IMS), inspiratory muscle endurance (IME), peak power, and oxygen uptake of recreational cyclists; and to compare these results with moderate-intensity IMT (60% of maximal inspiratory pressure [MIP]). Methods: Thirty apparently healthy male recreational cyclists, 20–40 years old, underwent 11 weeks of IMT (3 times per week; 55 min per session). Participants were randomized into 3 groups: sham group (6 cmH2O; n = 8); 60% MIP (MIP60; n = 10) and CIP (n = 12). All participants performed the IMS test and incremental IME test at the first, fifth, ninth, and 13th weeks of the experimental protocol. Cardiopulmonary exercise testing was performed on an electromagnetic braking cycle ergometer pre-IMT and post-IMT. Data were analyzed using a 2-way repeated measures ANOVA (group and period factors). Results: IMS increased in CIP and MIP60 groups at the ninth and 13th weeks compared with the sham group (P < .001; β = 0.99). Regarding IME, there was an interaction between the CIP and MIP60 groups in all periods, except in the initial evaluation (P < .001; β = 1.00). Peak power (in watts) increased after IMT in CIP and MIP60 groups (P = .01; β = 0.67). Absolute oxygen uptake did not increase after IMT (P = .49; β = 0.05). Relative oxygen uptake to lean mass values did not change significantly (P = .48; β = 0.05). Conclusion: High-intensity IMT is beneficial on IMS, IME, and peak power, but does not provide additional gain to moderate intensity in recreational cyclists.

Restricted access

Antonio Henrique Germano-Soares, Rafael M. Tassitano, Breno Quintela Farah, Aluísio Andrade-Lima, Marília de Almeida Correia, Aleš Gába, Nikola Štefelová, Pedro Puech-Leao, Nelson Wolosker, Gabriel Grizzo Cucato, and Raphael Mendes Ritti-Dias

Background: To examine the associations between physical activity (PA) and sedentary behavior (SB) with walking capacity and the effects of reallocating time from SB to PA in patients with symptomatic peripheral artery disease (PAD) using compositional data analysis. Methods: This cross-sectional study included 178 patients (34% females, mean age = 66 [9] y, body mass index = 27.8 [5.0] kg/m2, and ankle-brachial index = 0.60 [0.18]). Walking capacity was assessed as the total walking distance (TWD) achieved in a 6-minute walk test, while SB, light-intensity PA, and moderate to vigorous-intensity PA (MVPA) were measured by a triaxial accelerometer and conceptualized as a time-use composition. Associations between time reallocation among wake-time behaviors and TWD were determined using compositional isotemporal substitution models. Results: A positive association of MVPA with TWD (relative to remaining behaviors) was found in men (βilr = 66.9, SE = 21.4, P = .003) and women (βilr = 56.5, SE = 19.8; P = .005). Reallocating 30 minutes per week from SB to MVPA was associated with higher TWD in men (6.7 m; 95% confidence interval, 2.6–10.9 m) and women (4.5 m; 95% confidence interval, 1.5–7.5 m). Conclusions: The findings highlight, using a compositional approach, the beneficial and independent association of MVPA with walking capacity in patients with symptomatic PAD, whereas SB and light-intensity PA were not associated.

Restricted access

Michael J. Shoemaker, Michaela Mattern, Hannah Scholten, Jessica Zeitler, and Shweta Gore

Background: The measurement of daily physical activity (DPA) is important for the prognosis and quantifying clinical outcomes in individuals with heart disease. The measurement of DPA is more feasible using subjective measures when compared with objective measures. The purpose of this systematic review of the literature was to identify the subjective measures of DPA that have established reliability and validity in individuals with heart disease to assist clinician and researcher instrument selection. Methods: A systematic search of PubMed, CINAHL, MEDLINE, and ProQuest databases was performed. Methodological rigor was assessed using 3 different quality appraisal tools. Qualitative synthesis of included studies was performed. Results: Twenty-two unique studies covering 19 subjective DPA measures were ultimately included. Methodological rigor was generally fair, and validity coefficients were moderate at best. Conclusions: Only 4 subjective measures that have established test–retest reliability and that provide an estimate of energy expenditure, metabolic equivalents, or minutes of DPA were compared against accelerometry or a DPA diary in patients with heart disease: SWISS Physical Activity Questionnaire, Total Activity Measure 1 and 2, and Mobile Physical Activity Logger. Depending on the clinician or researcher needs, instrument selection would depend on the recall period and the DPA construct being measured.

Restricted access

Adrien Vachon, Nicolas Berryman, Iñigo Mujika, Jean-Baptiste Paquet, and Laurent Bosquet

Purpose: To assess the effects of a short-term taper on the ability to perform repeated high-intensity efforts, depending on players’ fatigue level following an intensive training block. Method: After a 3-day off-season camp, 13 players followed the same 3-week preseason training block followed by a 7-day exponential taper. Performance was assessed by a repeated high-intensity effort test before and after the taper. Total sprint time, percentage of decrement, and the number of sprints equal to or higher than 90% of the best sprint were retained for analysis. Players were a posteriori classified in normal training or acute fatigue groups based on their readiness to perform prior to the taper, assessed through the magnitude of difference in psychological (Profile of Mood State Questionnaire), cardiovascular (submaximal constant-duration cycling), and neuromuscular (countermovement jump) tests between the preintensive and postintensive training blocks. Results: Training load declined by 55% (9%) during the taper (P = .001, g = −2.54). The overall group showed a small improvement in total sprint time (−3.40% [3.90%], P = .04, g = −0.39) following the taper. Relative changes tended to be higher in the acute fatigue compared with the normal training group (−5.07% [4.52%] vs −1.45% [1.88%], respectively; P = .08; d = 1.01). No taper-induced improvement was observed in percentage of decrement or number of sprints equal to or higher than 90% of the best sprint. Conclusion: A 7-day taper consisting of 55% training load reduction improved repeated high-intensity effort performance in young elite rugby union players. Pretaper level of fatigue seems to be a key determinant in the taper supercompensation process, as acutely fatigued players at the end of the intensive training block tended to benefit more from the taper.