Journal of Sports Medicine and Physical Fitness最新文献

Background: Asymmetry of propulsion is a key factor when the movements of two limbs occur in sequence. Considering the difficulties in quantifying thrust forces during free-swimming, tethered-swimming is proposed as an alternative tool. The purpose of this study was to investigate the thrust forces during tethered and free-swimming, including the effect of hand dominance.

Methods: Eleven swimmers were analyzed during 10-s all-out front-crawl swimming test in both conditions using only arms. Two pressure sensors were attached to each swimmer's hand (palmar and dorsal side) to estimate the propulsive forces as the horizontal component of the product of hand differential pressure and hand surface. Propelling forces in terms of average (FMEAN), impulse (I), peak (FPEAK), and as a pattern within the stroke cycle values were analyzed.

Results: Larger hand propulsion was found in tethered than in free-swimming (~16%, 11%, and 21%, for FMEAN, FPEAK, and I, respectively). The SPM analysis highlighted larger values only at the beginning of the cycle (from 7% to 42%). Dominance analysis revealed a higher FPEAK (~12 N) in the dominant limb than in the nondominant limb in both swimming conditions.

Conclusions: Larger hand force in tethered than free-swimming conditions is explained by differences from entry to catch phase.

Background: Mass participation in amateur cycling events is popular, and ensuring participant safety is crucial. This study aimed to determine the epidemiology of medical encounters (MEs), including injury and illness, at mass-participation amateur cycling events and to explore associated risk factors.

Methods: We conducted a cross-sectional, descriptive, exploratory analysis of operational data collected during the 2015-2016 94.7 Ride Joburg cycling race. Outcomes include frequency (N., %), prevalence (%), incidence (injuries/1000 participants), did-not-finish (DNF, %), and Odds Ratio (OR, 95%CI).

Results: In total, 44849 individuals, mean age 40.06±11.68, participated in the 94.7 Ride Joburg cycling race during 2015-2016. We report the prevalence for MEs (5.3%) (injury: 1.7%, illness: 3.6%). The incidence of all MEs was 52.71 (50.61-54.88) (injury: 16.79 [15.61-18.03], illness: 35.92 [34.19-37.72]). Most race participants were male (79.0%), aged 31-50 (58.9%). Older age decreased the odds of injury, illness, or not finishing (P<0.001). Females had higher odds of injury (OR:1.43; 1.21-1.67; P<0.001) and for DNF (OR:1.57; 1.46-1.70; P<0.001) but lower odds of illness (OR:0.73; 0.64-0.64; P<0.001), compared to males. Overall, 7.9% of participants DNF, 6.9% had MEs, 3.2% were injured, and 3.8% were ill. Medical point location and distance were not significantly associated with medical encounters.

Conclusions: Older participants have lower odds of injury and illness encounters. Females have higher odds of injury encounters and not finishing the race but lower odds of illness encounters than males. These findings offer insights into injury and illness at mass-participation amateur cycling events.

Background: The oxygen uptake efficiency slope (OUES) is a submaximal, effort-independent index derived from cardiopulmonary exercise testing that reflects aerobic fitness. Although OUES has shown strong correlations with maximal oxygen uptake (VO2max) in clinical populations, its validity and relationship with habitual physical activity in healthy middle-aged adults remain underexplored. This study aimed to evaluate OUES as a marker of aerobic fitness and examine its association with self-reported physical activity in this demographic.

Methods: Twenty-one middle-aged adults (14 women, seven men; mean age 63.3±3.8 years) without known cardiopulmonary disease were recruited. Participants completed the Sports Medicine Australia pre-exercise screening questionnaire, including weekly physical activity reporting. Each participant underwent a graded treadmill test (Bruce protocol) to submaximal effort, with oxygen uptake (VO2) and ventilation (VE) measured continuously using a validated portable metabolic system. OUES was calculated from the linear regression of VO2 against the log10VE). VO2max was estimated via a resting seismocardiography device (VentriJect Seismofit^®). Pearson's correlations and one-way ANOVA were used to evaluate relationships between variables and tertile-based fitness groups. An independent-samples t-test compared OUES values by sex.

Results: Mean peak VO2 was 25.2±4.1 mL/kg/min; mean OUES was 1629.6±522.0 mL/min per log L/min. OUES showed a moderate but non-significant correlation with estimated VO2max (r=0.415, P=0.069) and no meaningful association with self-reported physical activity (r=-0.012, P=0.960). One-way ANOVA showed significant differences in VO2max across VentriJect VO2 tertiles (P<0.001, η²=0.65), but not in OUES (P=0.162). Males had significantly higher OUES values than females (2171±391 vs. 1366±282; P<0.001), with a large effect size (Cohen's d=2.50).

Conclusions: OUES can be reliably obtained using a brief treadmill protocol and portable metabolic equipment in middle-aged adults. While not associated with self-reported activity, OUES showed moderate correlations with VO2max and differentiated higher-fitness individuals, especially by sex. These findings support OUES as a valid submaximal marker of cardiorespiratory fitness and underscore the importance of objective fitness measures alongside self-report tools in health and exercise settings.

Background: This study analyses whether sweep rowers (port, starboard), who in the boat row in an asymmetric movement, sit on the seat of the rowing ergometer in a different manner from scullers, who on the boat row in symmetric manner.

Methods: Twenty-five male rowers (9 scull and 16 sweep: 8 port and 8 starboard) each performed a 90-min endurance training on rowing ergometer. Any displacement sideways of the rowers on the seats was measured from images of back of the rower at 30, 60 and 90 min.

Results: Scullers were seated in the expected manner maintaining centrality of the seat (distance from center at 30, 60, 90 min = 0.3±0.5 cm; 0.3±0.5 cm, 0.6±0.5 cm) in contrast with portside rowers who shifted to the left (30, 60, 90 min = -3.0±1.1 cm; -3.6±1.1 cm; -3.5±0.9 cm) and starboard rowers who shifted to the right (30, 60, 90 min = 3.1±2 cm; 3.9±1.6 cm; 3.4±1.4 cm). Shifted seating for sweep rowers was consistently observed to the opposite side to which they rowed.

Conclusions: The type of rowing on the boat influenced how rowers sit on the ergometer with sweep rowers consistently adopting a seating position shifted to opposite side to the one they rowed. This can be interpreted in terms of neural memory of prior postural adjustments and calls for further monitoring as asymmetry in seating may lead to uneven loading, particularly relevant to athletes with large training volume and density and when rowing in more "extreme" rowing settings, for example, coastal rowing / beach sprints events.

Introduction: This study evaluated and quantified the effects of plyometric training (PT) on soft versus rigid surfaces on jump, sprint, and agility performance.

Evidence acquisition: A literature search was conducted using PubMed, CINAHL, Embase, SportDiscuss, and Web of Science from January 1980 to April 2024. Randomized controlled trials examining PT interventions on the lower limbs with surface descriptions were included. Data extracted by two independent reviewers comprised: 1) the name of the first author and year of publication; 2) study design and participant characteristics; 3) PT program details; and 4) main outcome measures.

Evidence synthesis: The meta-analysis revealed that soft-surface PT significantly increased the vertical jump height (standardized mean difference [SMD], 0.83; [95% confidence interval [CI] 0.59, 1.07]), while rigid-surface PT also produced significant improvements in jump height (SMD, 0.98; [95% CI 0.68, 1.28]). For horizontal jump performance, soft-surface PT showed significant effects (SMD, 0.96; [95% CI 0.64, 1.27]), while rigid-surface PT demonstrated moderate effects (SMD, 0.78; [95% CI 0.5, 1.05]). Both soft- and rigid-surface PT significantly reduced sprint time (SMD, -1.03; [95% CI -1.24, -0.81] and SMD, -0.89; [95% CI -1.22, -0.57], respectively) and enhanced agility performance (SMD, -1.07; [95% CI -1.34, -0.80]).

Conclusions: PT significantly enhanced physical performance outcomes, regardless of the surface type. Practitioners may not need to prioritize the specific surface type when implementing PT programs aimed at improving jump, sprint, and agility performances.

Background: Multimodal training characterized by diverse, large, and novel bone strains improves bone mass, but after menopause the evidence is inconsistent. This intervention evaluated the osteogenic efficacy of multimodal high-intensity gymnastics for postmenopausal women.

Methods: Thirty-three healthy women participated in a 19-week controlled intervention followed by 11-weeks detraining: Group I (N.=21): 3x30 min fully supervised and personalized gymnastics weekly (age 57.1±4.8 yrs; weight 64.5±8.1 kg; BMI 22.9±2.9 kg/m²; VO2max 30.3±3.9 mL/kg/min [mean±SD]). Group C (N.=12): Controls (age 57.9±3.9 yrs; weight 63.9±10.6 kg; BMI 22.7±3.0 kg/m²; VO2max 30.4±4.9 mL/kg/min [mean±SD]). Primary outcomes: lumbar spine (L1-L4) and total proximal femur (TPF) bone mineral density (BMD) (g/cm²) and markers of bone formation (procollagen type-I amino-terminal propeptide [PINP] and osteocalcin [OC] µg/L) and resorption (C-terminal telopeptide of type-I collagen [CTX-I], ng/L).

Results: Post-intervention, percent ΔBMD (mean±SEM) were larger for I than C in L1-L4 (0.9±0.5% vs. -1.1±0.8%, P<0.05) and right (0.8±0.4% vs. -1.0±0.3%, P<0.005) and left (0.7±0.3% vs. -0.5±0.3%, P<0.05) TPF. Percent ΔOC (mean±SEM) were larger (P<0.005) for I than C after 3 weeks (11.7±20.5% vs. -9.3±19.4%), 12 weeks (23.7±17.6% vs. -11.5±29.0%) and post-intervention (18.0±25.9% vs. -14.8±28.6%). Percent ΔPINP and ΔCTX-I did not differ between I and C, despite consistent significant increases in PINP for I. Following detraining, percent ΔBMD between-group differences had increased further in L1-L4 (P<0.005) and right TPF (P<0.001).

Conclusions: The osteogenic impact of 19-weeks high-intensity gymnastics for postmenopausal women was significant and consistent regardless of the assessment method. Thus, gymnastics proved to be effective to counteract the postmenopausal BMD reductions.

Background: Introduced in the mid-1990s and recently recognized as an Olympic sport, kitesurfing combines surfing, windsurfing, and wakeboarding. Despite its growing popularity and high-speed maneuvers that heighten injury risks, there is a significant gap in research on the epidemiological aspects of injuries. This study aims to evaluate the prevalence, patterns, and factors related to orthopedic injuries among kitesurfers. The secondary outcomes focus on characteristics associated with injuries, treatment options, duration of absence from sports, and subsequent effects on performance. These findings underscore the urgent need for developing effective safety protocols to mitigate these risks.

Methods: This cross-sectional study utilized a convenience sample of kitesurfing athletes aged 18 years or older, each with at least one year of experience, recruited through the Brazilian Kitesurfing Association. Participants completed an online questionnaire detailing their personal details, kitesurfing specifics and injury-related data.

Results: A total of 442 kitesurfers, aged 18 to 70 (mean 41.9 years), were included. Findings show that 66.6% of athletes reported injuries, more frequently among more experienced, especially those classifying themselves as advanced. Most injuries occurred during training within 50 meters of the shore, under moderate wind speeds (11-27 knots), and mainly affected the knee, foot, or ankle.

Conclusions: The findings highlight the necessity for improved safety protocols and injury prevention measures in kitesurfing. Given the sport's rising popularity and inherent risks, these measures are crucial to reduce injury rates and mitigate their impact on performance and sport continuity. Additionally, kitesurfing's Olympic inclusion underscores the importance of global safety concerns.

Background: Running has increased in popularity as a form of exercise, and with it, the incidence of running-related injuries. Barefoot running has gained attention as a strategy to potentially reduce injury risk, though empirical evidence supporting this remains limited. The purpose of this study was to compare injury incidence between barefoot and shod runners based on self-reported history.

Methods: A total of 545 participants completed a survey assessing their running patterns and injury history. Descriptive and inferential analyses were conducted to examine associations between footwear type and injury incidence.

Results: Statistical analyses were performed showing strong association between the barefoot group and reduced reports of injury. A post-hoc matched-pair analysis of 21 barefoot runners and 21 shod runners (matched by age, gender, and BMI) indicated a significantly lower reported injury rate among barefoot runners (P=0.011).

Conclusions: These findings suggest that barefoot running was associated with a lower risk of injury in a matched subgroup, although further research is needed to confirm these results.

Introduction: While it is understood that resistance exercise in humans induces muscle growth primarily via muscle hypertrophy, there is some debate as to whether muscle hyperplasia also occurs. The purpose of this meta-analysis was to quantitively assess whether the presence of muscle hyperplasia occurs in humans performing resistance training.

Evidence acquisition: Medline, Scopus, and Web of Science were searched on May 17, 2024. Studies that measured or reported sufficient data to estimate muscle fiber number before and after resistance training were included in a three-level random effects model. Fiber number was estimated from the ratio of muscle cross-sectional area to fiber cross-sectional area.

Evidence synthesis: A total of 11 studies met the inclusion criteria. Changes in fiber number were estimated in the biceps brachii or vastus lateralis muscles. Meta-analysis results indicated that resistance exercise did not significantly alter the estimated number of muscle fibers (ES: 4086; 95% CI: -6430, 14,604; P=0.419). Additionally, the presence of muscle hyperplasia was not moderated by prior training status, training duration, or the muscle group analyzed (all P>0.05).

Conclusions: These findings suggest that meaningful changes in muscle fiber number are unlikely to occur in humans following resistance training interventions lasting up to 6 months. While muscle hyperplasia was not evident, it may be difficult to detect due to the relatively short duration of the included training interventions and/or difficulties in estimating muscle fiber number, which resulted in a wide range of estimates across studies.

Introduction: The development of Advanced Footwear Technology (AFT) has introduced significant changes in the realm of athletic footwear, promising enhancements in running economy and reductions in energy cost compared to traditional shoes. This systematic review aims to analyze and synthesize the existing literature on AFT, focusing on its physical, physiological, biomechanical, and perceptual impacts on athletic performance. It seeks to identify key findings, variability, and implications for athletes by comparing AFT to traditional footwear.

Evidence acquisition: Following the PRISMA 2015 guidelines for systematic reviews, a comprehensive search was conducted in PubMed, Scopus, Web of Science, and Google Scholar. Titles, abstracts, and full texts were analyzed based on predefined inclusion criteria to find relevant studies. The methodological quality of the selected studies was also assessed.

Evidence synthesis: Nine studies (N.=138 participants) were included, with an average methodological quality score of 6.22 (range: 5 to 8) on a 10-point scale. AFT was found to improve biomechanical aspects, which were associated with enhanced running efficiency, and reduce metabolic energy expenditure. However, improve biomechanical aspects, which were associated with enhanced running efficiency.

Conclusions: AFT offers significant performance and biomechanical benefits, but its physiological effects vary, and potential injury risks such as altered lower-limb stiffness and increased joint load require careful management. Personalized approaches to footwear technology are crucial to maximizing AFT's benefits.