Journal of Sports Medicine and Physical Fitness最新文献

Background: Low back pain is prevalent among various populations and greatly impacts their quality of life. Professions that incorporate several working hours combined with heavy labor are the most affected. The aim of this study was to examine the effects of an 8-week core training intervention in emergency personnel.

Methods: Sixteen randomly selected male participants; police officers (N.=8) and firefighters (N.=8) (mean age: 40.75 years; mean height: 177.69 cm; mean body mass: 85.50 kg) performed various testing procedures that assessed core muscle strength and endurance and filled the Oswestry Disability Index Questionnaire regarding the level of low back pain before and after the intervention. The 8-week intervention consisted of two 45-60-minute sessions per week that included ten core-related exercises.

Results: Statistical analysis; paired samples t-test and Wilcoxon Signed-Rank Test, demonstrated significant effects in the 30-sec sit-up test, the Double Leg Lowering Test and the isometric abdominal strength measurements; P value level of significance was set at P≤0.05. All participants had minimal lower back disability before and after the intervention.

Conclusions: The results demonstrated that the prescribed regime could improve core strength and endurance in high-risk professionals. The most important finding is that training interventions for emergency personnel are most effective when they incorporate a variety of exercises that target the core musculature in all planes of movement and engage the whole range of motion.

Background: Understanding the evolution of morphological features and their relationship with physical performance may assist coaches and institutions in developing the next generation of beach volleyball (BV) athletes for senior-level competition. Thus, this study analyzed the morphological features of Brazilian BV athletes by sex among age groups, and their relationship with physical performance.

Methods: A cross-sectional design was used to evaluate Brazilian BV players of both sexes in the U15 (11-14 years old, N.=21), U18 (15-17 years old, N.=21) and Senior (≥18 years old, N.=19) categories. The players underwent a series of kinanthropometric tests, including morphological (anthropometry, body composition and somatotype), neuromuscular (flexibility, handgrip strength, vertical jump [VJ], agility, and 5-m and 10-m maximum-speed sprints), and metabolic (VO2max) measurements. Welch analysis of variance (ANOVA) was used to compare the categories and the relationship between morphological and physical performance features was analyzed using Pearson's coefficient (r).

Results: Significant differences were found among the categories for female (body mass, skeletal muscle mass, hamstring flexibility, handgrip strength [HGS]) and male (body mass, height, BMI, skeletal muscle mass, flexibility, HGS, vertical jump, agility, maximum-speed sprints, and VO2max) players. Moreover, moderate, and strong correlations were identified between morphological features and physical performance (-0.90≤r≤0.89).

Conclusions: The morphological and physical performance features of BV athletes varied among the U15, U18, and Senior categories, as expected due to their physical training process. Additionally, there are several morphological features that are correlated with physical performance, but the magnitude seems to depend on sex and category.

The detection of myocardial scar tissue profoundly influences athletes care and prognostic categorization. Athletes appear to be at risk of developing fatal arrhythmias when harboring a quiescent cardiac disorder. Early identification of disease in asymptomatic individuals through preparticipation screening is means to prevent these events. We presented a male marathon runner master athlete who came at our Department of Sports Medicine for a preparticipation screening. Baseline 12-lead standard electrocardiogram was normal. A maximal cycle ergometer exercise test revealed exercise-induced premature ventricular contractions (PVCs) with uncommon morphology. Echocardiography revealed an hyperechogenic zone at mid-basal posterior segments of the left ventricle. Twenty-four-hours ECG Holter monitoring, with training session, showed some isolated polymorphic PVCs even during training session. Cardiac magnetic resonance (CMR) confirmed the presence of a non-ischemic left ventricular scar (subepicardial) into the mid-basal segment of the posterior wall. Echocardiography is a first-line, economic, and accessible diagnostic test for athletes and it can be useful, when abnormalities are detected, to indicate further investigations, such as CMR. Although non-ischemic left ventricular scarring is difficult to detect on echocardiography, this event is sometimes possible and require further investigation when observed.

Background: Sprint interval training (SIT) has been shown to improve many indices of cardiovascular risk. The effect of SIT on emerging indicators of cardiovascular health, including arterial stiffness and carotid intima media thickness, remains unclear. Thus, the purpose of this study was to assess changes in augmentation index at 75 beats per minute (AIx@75), pulse wave velocity (cfPWV), and carotid intima media thickness (CIMT) at three time points of an 8-week SIT intervention.

Methods: Eighteen sedentary men (age: 24.7±5.1 years, BMI: 26.7±5.8 kg/m²) participated in the study. Subjects trained 3 times a week for 8 weeks. Training consisted of 3-6 consecutive 30-second bouts of maximal intensity cycling, with 4.5 minutes of active recovery between bouts. Baseline, 4-week, and 8-week vascular assessments were performed. Training effects were analyzed using repeated measures ANOVA. Pearson correlations were used to determine the relationship between baseline values and the change scores (baseline to 8 weeks) of each vascular measure.

Results: AIx@75 (BL: -3.6±10.9%, 4W: -5.6±8.3%, 8W: -3.2±9.5%), cfPWV (BL: 5.6±1.0 m/s, 4W: 5.8±0.9 m/s, 8W: 5.6±0.7 m/s), and CIMT (BL: 0.51±0.08 mm, 4W: 0.52±0.08 mm, 8W: 0.51±0.08 mm) did not significantly change (all P>0.05). Baseline cfPWV and AIx@75 were negatively correlated to their change from baseline to 8 weeks (P<0.05).

Conclusions: These findings demonstrate that 8 weeks of SIT is an insufficient stimulus to reduce cfPWV, AIx@75, or CIMT in a group of young, healthy men. Baseline arterial stiffness may modulate vascular adaptations to SIT.

Background: Cardiorespiratory fitness is linked to various health outcomes. This study aimed to establish cut-off values for estimated cardiorespiratory fitness associated with poor physical functioning in middle-aged to older adults.

Methods: A total of 2638 participants (1083 males), aged 40-69 years, performed a 6-min walking test (6MWT) to estimate cardiorespiratory fitness (VO2max) and completed a health-related questionnaire. Physical functioning was assessed using four outcomes: perceived health, perceived fitness, difficulties in 2-km walking, and difficulties in climbing several stairs. Receiver operator characteristics (ROC) curves were used to determine cut-off values for estimated VO2max and 6MWT distance linked to poor physical functioning based on the four outcomes. Analyses were done separately for males and females, and for 40- to 49-, 50- to 59-, and 60- to 69-year-old groups. Multinomial regression was used to analyze differences between fitness thirds in outcome variables.

Results: ROC analyses were significant for all outcomes (AUC 0.686-0.834, P<0.001). In the total group, cut-off values for estimated VO2max were 29.9-30.2 mL/kg/min, and for walking distance, 588.0-599.5 m. Cut-off values decreased with age, and mean differences between males and females were 3.3 mL/kg/min and 33 m. All cut-off values were within ±1.3 mL/kg/min of the lower fitness tertile. The odds ratios of having poor physical functioning in the middle and high fitness thirds were less than 0.50 compared to low fitness third.

Conclusions: VO2max of 30 mL/kg/min and 600-m walking distance seemed reasonable cut-off values for poor physical functioning. Exceeding the currently proposed thresholds is a desirable goal to avoid consequences of insufficient fitness.

Background: This study aimed at assessing how chronic exposure to specific exercise training (high-intensity intervals vs. endurance), comparing experienced basketball-players (BP, N.=16), cyclists (CY, N.=16), and non-specifically trained individuals (CN, N.=16), influences the structural and functional characteristics of both lower limb and respiratory musculotendinous structures.

Methods: Vastus lateralis, gastrocnemius lateralis, and medialis, diaphragm muscles, as well as patellar tendon and Achilles tendon, were assessed using B-mode ultrasonography. Maximal voluntary isometric and passive torque measurements were conducted in the knee-extensors and plantar-flexors. Additionally, a subset of participants (N.=10 for each group) underwent a fatigue-inducing exercise-till-exhaustion protocol, and the strength of lower limb and respiratory muscles was evaluated immediately before and after the trial.

Results: Athletes had bigger and stronger musculotendinous structures and greater endurance to fatigue than CN (P<0.05). BP had bigger plantar-flexors and diaphragm, greater fascicles length, more explosive plantar-flexors and respiratory muscles and bigger tendons than CY (P<0.05). On the other hand, CY showed greater muscle pennation angle and greater endurance to fatigue for both, lower limb, and respiratory muscles (P<0.05).

Conclusions: The present study emphasizes that chronic and specific exercise training leads to distinctive adaptations, not only in lower limb musculotendinous structures but also in other components such as respiratory muscles.

Background: Central Augmentation Index (AIx) is a surrogate marker of large artery stiffness that may provide valuable insight to cardiovascular health. The aim of this study was to evaluate the relationship between AIx and components of physical fitness.

Methods: One hundred eighty-five healthy men and women (aged 20-79 years) underwent non-invasive assessment of arterial wave reflection to determine AIx, which was corrected to a heart rate of 75 beats per minute (AI×75). Body composition was evaluated using dual energy X-ray absorptiometry (DXA) and aerobic capacity (VO2max) was derived from expired gas analysis during a symptom limited exercise test on a treadmill.

Results: A multiple linear regression revealed age and VO2max as significant predictors of AI×75 [AI×75=32.055 + (0.252×age) - (0.722×VO2max)]. Upon removal of VO2max from regression analysis, resting heart rate (RHR) and % body fat (BF%) were revealed to be significant predictors of AI×75: AI×75=-61.316 + (0.481×age) + (0.565×BF%) + (0.56×RHR).

Conclusions: Our findings demonstrate that central Augmentation Index can be reliably predicted in healthy adults who undergo a maximal exercise or body composition assessment. These prediction equations may be applied in non-medical settings to assist in creating comprehensive health and fitness profiles for healthy clientele.

Background: Hamstring strains may alter the contractile properties of the muscle and affect functional movement. Thus, this study evaluated the association between the hamstring properties and the jump-landing performance in athletes with hamstring strains.

Methods: Sixteen hamstring-injured athletes and 16 healthy controls were recruited. The mechanical properties and contractile function of the hamstring were assessed in both the injured and non-injured legs. The control group was tested only in the matched injured leg. The kinetic outcomes during squat jump (SJ) and countermovement jump (CMJ) tasks were analyzed to evaluate the jump-landing performance.

Results: The injured limb exhibited higher muscle tone (P=0.042) and stiffness (P=0.010), but lower flexibility (P=0.002) and strength (P=0.040) than the control limb. The injured limb showed a poorer jumping performance (P=0.037 for jump height) and landing performance (P=0.011 for landing force and P=0.004 for loading rate) during the CMJ task compared to the control limb. All the hamstring properties showed mild-to-moderate correlations with the jump-landing performance.

Conclusions: Impairments in the muscle properties following hamstring strain impact the jumping and landing performance, leading to degraded sports outcomes in athletes with hamstring injuries. Thus, more attention should be paid to tissue property changes following hamstring strain injuries to develop effective strategies for restoring muscle function and improving sports performance.

Background: Freediving is a sport that could be defined as both aerobic and anaerobic. Therefore, this study aimed to evaluate the effect of aerobic-anaerobic training on the performance of moderate and elite freedivers.

Methods: The sample of participants included 26 freedivers (9 females) (average age of 26.62±3.34 years, body height of 178.95±9.19 cm, and body mass of 74.64±11.97 kg). The sample of variables included: anthropometric indices, relative maximal oxygen consumption (rVO2max), Diving anaerobic sprint test (DAST), Swimming anaerobic sprint test (SAST), 100-meter crawl sprint test (100 m), maximal dynamic apnea with monofin (DYN), maximal swimming length for 2 minutes (2 min). The study procedure included a 5-month aerobic-anaerobic training intervention. This intervention was conducted during a 4-phase (5-week each) training period.

Results: The results showed that moderate group showed a significant decrease in 100 m (final 83.94±15.68; initial 88.29±16.73; P<0.00), DASTmax (final 10.91±1.46; initial 12.01±1.38; P<0.00), DAST (final 70.29±8.95; initial 79.40±10.25; P<0.00), SASTmax (final 16.81±2.24; initial 18.01±2.69; P<0.00), SAST(final 112.87±19.19; initial 122.65±21.55; P<0.00), and increase in 2 min (final 140.56±21.53; initial 128.68±19.33; P<0.00), and DYN (final 130.48±26.89; initial 91.65; P<0.00). Similarly, the elite group experienced a decrease in 100 m (final 72.18±9.77; initial 75.00±11.36; P=0.02), DASTmax (final 10.14±0.95; initial 10.88±0.99; P=0.03), DAST (final 65.55±6.50; initial 71.24±7.32; P=0.02), SASTmax (final 14.82±1.84; initial 15.76±1.80; P=0.03), and increase in DYN (final 194.94±27.70; initial 161.11±27.70; P<0.00).

Conclusions: The results of this study demonstrate that dynamic apnea, as a main performance factor, had increase in all phases of procedure, with highest increase during anaerobic phases.

Background: Endurance performance is impacted by physiological, anthropometrical, diet, genetic, psychological, and training characteristics. Altitude can affect physiological parameters (like maximum oxygen utilization, arterial oxygen saturation (SaO2), heart rate, and blood pressure) and training characteristics (duration, frequency, and training load). Thus, this study compared physiological parameters and training characteristics between endurance runners at Ethiopian Youth Sports Academy (EYSA) and Guna Athletics Sport Club (GASC) located which are located at elevation of 2400 and 3100 meters, respectively.

Methods: A comparative cross-sectional study design was used from September to November 2021. Data was obtained from a total of 120 eligible participants (30 runners and 30 controls at GASC, and 30 runners and 30 controls at EYSA). Sociodemographic and training characteristics were assessed using self-administered standardized questionnaires. SaO2 and heart rate were measured using finger pulse-oximetry (Nellcor, Oxim N-65; Covidien, Dublin, Ireland). Blood pressure was measured by Folee Digital Blood Pressure Monitor DX-B1 (Jiangsu Folee Medical Equipment Co., Ltd., Zhenjiang, China).

Results: The runners of GASC had significantly lower resting SaO2, SaO2 immediately after maximal exertion, training (frequency and load) than runners of EYSA in both sexes. Runners of Guna Athletics Sport Club (RGASC) had significantly higher maximum oxygen utilization (VO2max) than Runners Ethiopian Youth Sports Academy (REYSA) in both sexes. Severe exercise-induced hypoxemia (EIAH) and moderate EIAH were developed by male runners of GASC and EYSA respectively. Besides, female runners GASC and EYSA developed moderate and mild EIAH, respectively.

Conclusions: Conclusively, there were significant differences in physiological parameters and training load between RGASC and REYSA. High altitude (3100 meters) may have a greater impact on the above variables than moderate hypoxia (2400 meters above sea level). Hence, endurance runner coaches should give emphasis to these variables.