Lower-body compression garments worn following exercise improves perceived recovery but not subsequent performance in basketball athletes

ABSTRACT

This study examined the effects of lower-body compression garments on perceived recovery and subsequent performance in basketball athletes. In a parallel-group design, 30 recreational, male basketball athletes were randomly allocated to either a control (CON, n = 15, loose-fitting clothing) or experimental group (COMP, n = 15, compression garments) for 15 h following fatigue-inducing, basketball-specific exercise in the evening (1600-1800 h). Perceptual measures of fatigue and muscle soreness, as well as physical performance tests (sprints, jumps and agility), were performed pre-exercise, post-exercise, and post-recovery (15 h following exercise). Subjective and objective measures of sleep were recorded following the exercise trial. There were non-significant (p > 0.05), unclear-trivial differences between groups for all performance measures. Perceived post-recovery fatigue (d = ?1.27, large) and muscle soreness (d = ?1.61, large) were significantly lower in COMP compared to CON (p < 0.05). COMP exhibited better perceived sleep quality (d = 0.42, small, p = 0.18) than CON, with an unclear difference in sleep duration between groups (p > 0.05). Wearing lower-body compression garments overnight improved perceived fatigue and muscle soreness, but had negligible effects on subsequent physical performance in basketball athletes. Future research should focus on longer periods of compression wear following fatiguing exercise.     

The influence of wearing compression stockings on performance indicators and physiological responses following a prolonged trail running exercise

Abstract

The objective of this study was to investigate the effects of wearing compression socks (CS) on performance indicators and physiological responses during prolonged trail running. Eleven trained runners completed a 15.6 km trail run at a competition intensity whilst wearing or not wearing CS. Counter movement jump, maximal voluntary contraction and the oxygenation profile of vastus lateralis muscle using near-infrared spectroscopy (NIRS) method were measured before and following exercise. Run time, heart rate (HR), blood lactate concentration and ratings of perceived exertion were evaluated during the CS and non-CS sessions. No significant difference in any dependent variables was observed during the run sessions. Run times were 5681.1±503.5 and 5696.7±530.7 s for the non-CS and CS conditions, respectively. The relative intensity during CS and non-CS runs corresponded to a range of 90.5–91.5% HR_max. Although NIRS measurements such as muscle oxygen uptake and muscle blood flow significantly increased following exercise (+57.7% and + 42.6%,+59.2% and + 32.4%, respectively for the CS and non-CS sessions, P<0.05), there was no difference between the run conditions. The findings suggest that competitive runners do not gain any practical or physiological benefits from wearing CS during prolonged off-road running.     

Muscle – tendon unit mechanical and morphological properties and sprint performance

Abstract

The objective of this study was to determine whether sprint performance is related to the mechanical (elongation – force relationship of the tendon and aponeurosis, muscle strength) and morphological (fascicle length, pennation angle, muscle thickness) properties of the quadriceps femoris and triceps surae muscle – tendon units. Two groups of sprinters (slow, n = 11; fast, n = 17) performed maximal isometric knee extension and plantar flexion contractions on a dynamometer at 11 different muscle – tendon unit lengths. Elongation of the tendon and aponeurosis of the gastrocnemius medialis and the vastus lateralis was measured using ultrasonography. We observed no significant differences in maximal joint moments at the ankle and knee joints or morphological properties of the gastrocnemius medialis and vastus lateralis between groups (P > 0.05). The fast group exhibited greater elongation of the vastus lateralis tendon and aponeurosis at a given tendon force, and greater maximal elongation of the vastus lateralis tendon and aponeurosis during maximum voluntary contraction (P < 0.05). Furthermore, maximal elongation of the vastus lateralis tendon and aponeurosis showed a significant correlation with 100-m sprint times (r = ?0.567, P = 0.003). For the elongation – force relationship at the gastrocnemius medialis tendon and aponeurosis, the two groups recorded similar values. It is suggested that the greater elongation of the vastus lateralis tendon and aponeurosis of the fast group benefits energy storage and return as well as the shortening velocity of the muscle – tendon unit.     

Radial bone size and strength indices in male road cyclists,mountain bikers and controls

Abstract

Mountain biking (MB), unlike road cycling (RC) involves exposure to ground impact bone strain and requires upper-body muscle forces to maintain stability over uneven terrain and therefore may have differential effects on radial bone structure and strength. This study aimed to compare serum bone turnover marker concentration, 1-repetition maximum muscle strength and the radial proximal (diaphysis) and distal (metaphysis) bone structure [bone mineral content, total and cortical area (CoA), density and thickness, diameter and circumference], strength strain indices and muscle cross-sectional area (MCSA) using peripheral quantitative computed tomography (pQCT) between 30 male cyclists (18–34 years) MB (n = 10), RC (n = 10) and non-athletes controls (CON, n = 10). Differences were assessed by ANOVA and an ANCOVA (adjusting for body mass and height) where appropriate. MB radii were characterised by significantly stronger (14–16%), denser (9–27%) and larger (10%) metaphyses and stronger (22–23%) and larger (11–13%) diaphyses compared to RC and CON. RC had significantly 7% higher strength indices and 4% greater CoA and thickness than CON at the diaphysis, with no differences for other bone measurements. Serum C-terminal telopeptides of type-1 collagen concentration (bone resorption marker) was higher in RC than MB (p < 0.05) and above the age-reference range. MCSA and strength were greater in MB than RC (p < 0.05). Muscle forces generated during RC appear to produce an osteogenic stimulus to increase radial bone strength indices with minimal improvement in bone structure. However greater resorptive activity in RC suggests inadequate loading to support bone maintenance. In conclusion, bone loading, muscle size and strength of MB are superior to RC.     

Brachial artery characteristics and micro-vascular filtration capacity in rock climbers

Abstract

Rock climbers perform repeated isometric forearm muscle contractions subjecting the vasculature to repeated ischaemia and distorted haemodynamic signals. This study investigated forearm vascular characteristics in rock climbers compared to healthy untrained controls. Eight climbers (CLIMB) (BMI; 22.3, s = 2.0 kg/m², isometric handgrip strength; 46, s = 8 kg) were compared against eight untrained controls (CON) (BMI; 23.8, s = 2.6 kg/m², isometric handgrip strength; 37, s = 9 kg). Brachial artery diameter and blood flow were measured, using Doppler ultrasound, at rest and following 5-mins ischaemia (peak diameter) and ischaemic exercise (maximal dilation) to calculate flow mediated dilation (FMD) and dilatory capacity (DC). Capillary filtration capacity was assessed using venous occlusion plethysmography. Resting (4.30, s = 0.26 vs. 3.79, s = 0.39 mm), peak (4.67, s = 0.31 vs. 4.12, s = 0.45 mm) and maximal (5.14, s = 0.42 vs. 4.35, s = 0.47 mm) diameters were greater (P < 0.05) in CLIMB than CON, respectively, despite no difference in FMD (9.2, s = 2.6 vs. 8.7, s = 2.9%). Peak reactive hyperaemic blood flow (1136, s = 504 vs. 651, s = 221 ml/min) and capillary filtration capacity (3.8, s = 0.9 vs. 5.2, s = 0.7 ml.min^?1.mmHg^?1.100 ml tissue^?1 × 10^?3) were greater (P < 0.05) in CLIMB compared to CON, respectively. Rock climbers exhibit structural vascular adaptation compared to untrained control participants but have similar vascular function. This may contribute to the enhanced ability of climbers to perform repeated isometric contractions.     

Effects of compression garments on surface EMG and physiological responses during and after distance running

BackgroundThe few previous studies that focused on the effects of compression garments (CG) on distance running performance have simultaneously measured electromyogram, physiological, and perceptual parameters. Therefore, this study investigated the effects of CG on muscle activation and median frequency during and after distance running, as well as blood-lactate concentration and rating of perceived exertion (RPE) during distance running.MethodsEight healthy male recreational runners were recruited to randomly perform two 40 min treadmill running trials, one with CG, and the other with control garment made of normal cloth. The RPE and the surface electromyography (EMG) of 5 lower extremity muscles including gluteus maximus (GM), rectus femoris (RF), semitendinosus (ST), tibialis anterior (TA), and gastrocnemius (GAS) were measured during the running trial. The blood-lactate levels before and after the running trial were measured.ResultsWearing CG led to significant lower muscle activation (p < 0.05) in the GM (decreased 7.40%–14.31%), RF (decreased 4.39%–4.76%), and ST (decreased 3.42%–7.20%) muscles; moreover, significant higher median frequency (p < 0.05) in the GM (increased 5.57%) and ST (increased 10.58%) muscles. Wearing CG did not alter the RPE values or the blood-lactate levels (p > 0.05).ConclusionWearing CG was associated with significantly lower muscle activation and higher median frequency in the running-related key muscles during distance running. This finding suggested that wearing CG may improve muscle function, which might enhance running performance and prevent muscle fatigue.     

Muscle - tendon unit mechanical and morphological properties and sprint performance

The objective of this study was to determine whether sprint performance is related to the mechanical (elongation - force relationship of the tendon and aponeurosis, muscle strength) and morphological (fascicle length, pennation angle, muscle thickness) properties of the quadriceps femoris and triceps surae muscle - tendon units. Two groups of sprinters (slow, n = 11; fast, n = 17) performed maximal isometric knee extension and plantar flexion contractions on a dynamometer at 11 different muscle - tendon unit lengths. Elongation of the tendon and aponeurosis of the gastrocnemius medialis and the vastus lateralis was measured using ultrasonography. We observed no significant differences in maximal joint moments at the ankle and knee joints or morphological properties of the gastrocnemius medialis and vastus lateralis between groups (P > 0.05). The fast group exhibited greater elongation of the vastus lateralis tendon and aponeurosis at a given tendon force, and greater maximal elongation of the vastus lateralis tendon and aponeurosis during maximum voluntary contraction (P < 0.05). Furthermore, maximal elongation of the vastus lateralis tendon and aponeurosis showed a significant correlation with 100-m sprint times (r = -0.567, P = 0.003). For the elongation - force relationship at the gastrocnemius medialis tendon and aponeurosis, the two groups recorded similar values. It is suggested that the greater elongation of the vastus lateralis tendon and aponeurosis of the fast group benefits energy storage and return as well as the shortening velocity of the muscle - tendon unit.     

Effect of citrulline on post-exercise rating of perceived exertion,muscle soreness,and blood lactate levels: A systematic review and meta-analysis

BackgroundCitrulline is one of the non-essential amino acids that is thought to improve exercise performance and reduce post-exercise muscle soreness. We conducted a systematic review and meta-analysis to determine the effect of citrulline supplements on the post-exercise rating of perceived exertion (RPE), muscle soreness, and blood lactate levels.MethodsA random effects model was used to calculate the effect sizes due to the high variability in the study design and study populations of the articles included. A systematic search of PubMed, Web of Science, and ClinicalTrials.gov was performed. Eligibility for study inclusion was limited to studies that were randomized controlled trials involving healthy individuals and that investigated the acute effect of citrulline supplements on RPE, muscle soreness, and blood lactate levels. The supplementation time frame was limited to 2 h before exercise. The types and number of participants, types of exercise tests performed, supplementation protocols for L-citrulline or citrulline malate, and primary (RPE and muscle soreness) and secondary (blood lactate level) study outcomes were extracted from the identified studies.ResultsThe analysis included 13 eligible articles including a total of 206 participants. The most frequent dosage used in the studies was 8 g of citrulline malate. Citrulline supplementation significantly reduced RPE (n = 7, p = 0.03) and muscle soreness 24-h and 48-h after post-exercise (n = 7, p = 0.04; n = 6, p = 0.25, respectively). However, citrulline supplementation did not significantly reduce muscle soreness 72-h post-exercise (n = 4, p = 0.62) or lower blood lactate levels (n = 8, p = 0.17).ConclusionCitrulline supplements significantly reduced post-exercise RPE and muscle soreness without affecting blood lactate levels.     

Effects of different types of exercise on muscle mass,strength, function and well-being in elderly

Abstract

Poor muscle strength and physical function have been associated with higher risk of hospitalisation and lower well-being among the elderly. Physical training increases muscle strength, endurance and physical function as well as psychological outcomes. Exercise among older adults is often used to improve these variables, but few have compared the effects of different types of training in parallel independent groups. Thus, the aim of the present study was to investigate the effect of three different types of training on body composition, muscle strength, physical function and well-being in the elderly. A total of 118 community-dwelling older adults (mean age 74.3, s=4.6 years, 68% women) completed a 13-week randomised controlled exercise-trial involving four groups: traditional strength training (STG), functional strength training (FTG), endurance training (ETG) and control (CON). Stair climb with load improved more in FTG than CON (P<0.05), and the two strength groups performed better in the functional upper body test (P<0.05). STG increased strength more than CON in all exercises (P<0.001), while FTG increased strength more than CON in the chest press, shoulder press and knee extension (P<0.05). Lean body mass (LBM) increased in all training groups, which differed significantly from CON (P<0.05). ETG decreased their fat mass compared to CON (P<0.001). The only significant effect on well-being indices was improved life satisfaction in FTG at week 5 (P<0.05). We also observed significant correlations between change in some of the functional tests and change in positive affect.

All three types of training can enhance physical capacity. Functional strength training can be a cost effective form of training in terms of less demand for instructors and equipment and could be an effective way to improve physical function, strength and indices of well-being in the elderly.     

The Reliability of Aerobic Capacity (VO2max ) Testing in Adolescent Girls

Purpose: This study compared the relative peak torque and normalized electromyographic (EMG) mean frequency (MNF) responses during fatiguing isokinetic muscle actions for men versus women. Method: Twenty men (M _age ± SD = 22 ± 2 years) and 20 women (M _age ± SD = 22 ± 1 years) performed 50 maximal concentric isokinetic muscle actions of the leg extensors at a velocity of 180°/s while surface EMG signals were detected from the vastus lateralis, rectus femoris, and vastus medialis. The dependent variables were initial, final, and average peak torque; percent decline; the estimated percentage of fast-twitch fibers for the vastus lateralis; and the linear slope coefficients and y-intercepts for normalized EMG MNF versus repetition number. The data were analyzed with independent-samples t tests and 2-way mixed-factorial analyses of variance. Results: The mean initial, final, and average peak torque values for men were greater than those for women. There were no mean differences for percent decline and the estimated percentage of fast-twitch fibers for the vastus lateralis. There were also no sex differences for the linear slope coefficients, but there were differences among the muscles (vastus medialis>vastus lateralis>rectus femoris). The mean y-intercept for the vastus lateralis for men was greater than that for women. Conclusions: Men demonstrated greater peak torque values than those for women, but the declines in peak torque and normalized EMG MNF were similar between the sexes. The vastus medialis was more fatigue-resistant than both the vastus lateralis and rectus femoris.     

Relationship of proprioception,cutaneous sensitivity,and muscle strength with the balance control among older adults

BackgroundBalance impairment is one of the strongest risk factors for falls. Proprioception, cutaneous sensitivity, and muscle strength are 3 important contributors to balance control in older adults. The relationship that dynamic and static balance control has to proprioception, cutaneous sensitivity, and muscle strength is still unclear. This study was performed to investigate the relationship these contributors have to dynamic and static balance control.MethodsA total of 164 older adults (female = 89, left dominant = 15, age: 73.5 ± 7.8 years, height: 161.6 ± 7.1 cm, weight: 63.7 ± 8.9 kg, mean ± SD) participated in this study. It tested the proprioception of their knee flexion/extension and ankle dorsi/plantarflexion, along with cutaneous sensitivity at the great toe, first and fifth metatarsals, arch, and heel, and the muscle strength of their ankle dorsi/plantarflexion and hip abduction. The Berg Balance Scale (BBS) and the root mean square (RMS) of the center of pressure (CoP) were collected as indications of dynamic and static balance control. A partial correlation was used to determine the relationship between the measured outcomes variables (BBS and CoP-RMS) and the proprioception, cutaneous sensitivity, and muscle strength variables.ResultsProprioception of ankle plantarflexion (r = –0.306, p = 0.002) and dorsiflexion (r = –0.217, p = 0.030), and muscle strength of ankle plantarflexion (r = 0.275, p = 0.004), dorsiflexion (r = 0.369, p < 0.001), and hip abduction (r = 0.342, p < 0.001) were weakly to moderately correlated with BBS. Proprioception of ankle dorsiflexion (r = 0.218, p = 0.020) and cutaneous sensitivity at the great toe (r = 0.231, p = 0.041) and arch (r = 0.285, p = 0.002) were weakly correlated with CoP-RMS in the anteroposterior direction. Proprioception of ankle dorsiflexion (r = 0.220, p = 0.035), knee flexion (r = 0.308, p = 0.001) and extension (r = 0.193, p = 0.040), and cutaneous sensitivity at the arch (r = 0.206, p = 0.028) were weakly to moderately correlated with CoP-RMS in the mediolateral direction.ConclusionThere is a weak-to-moderate relationship between proprioception and dynamic and static balance control, a weak relationship between cutaneous sensitivity and static balance control, and a weak-to-moderate relationship between muscle strength and dynamic balance control.     

Biceps femoris long head sarcomere and fascicle length adaptations after 3 weeks of eccentric exercise training

Background:Eccentric exercise increases muscle fascicle lengths;however,the mechanisms behind this adaptation are still unknown.This study aimed to determine whether biceps femoris long head(BFlh)fascicle length increases in response to 3 weeks of eccentric exercise training are the result of an in-series addition of sarcomeres within the muscle fibers.Methods:Ten recreationally active participants(age=27±3 years;mass=70±14 kg;height=174±9 cm;mean±SD)completed 3 weeks of Nordic hamstring exercise(NHE)training on a custom exercise device that was instrumented with load cells.We collected in vivo sarcomere and muscle fascicle images of the BFlh in 2 regions(central and distal)by using microendoscopy and 3 dimension ultrasonography.We then estimated sarcomere length,sarcomere number,and fascicle length before and after the training intervention.Results:Eccentric knee flexion strength increased after the training(15%;p<0.001;η_p²=0.75).Further,we found a significant increase in fascicle length(21%;p<0.001;η_p²=0.81)and sarcomere length(17%;p<0.001;ηp2=0.90)in the distal but not in the central portion of the muscle.The estimated number of sarcomeres in series did not change in either region.Conclusion:Fascicle length adaptations appear to be heterogeneous in the BFlh in response to 3 weeks of NHE training.An increase in sarcomere length,rather than the addition of sarcomeres in series,appears to underlie increases in fascicle length in the distal region of the BFlh.The mechanism driving regional increases in fascicle and sarcomere length remains unknown,but we speculate that it may be driven by regional changes in the pas sive tension of muscle or connective tis sue adaptations.     

Responses to oral glucose challenge differ by physical activity volume and intensity: A pilot study

BackgroundOne-hour postprandial hyperglycemia is associated with increased risk of type 2 diabetes and cardiovascular disease. Physical activity (PA) has short-term beneficial effects on post-meal glucose response. This study compared the oral glucose tolerance test results of 3 groups of people with habitually different levels of PA.MethodsThirty-one adults without diabetes (age 25.9 ± 6.6 years; body mass index 23.8 ± 3.8 kg/m²; mean ± SD) were recruited and divided into 3 groups based on self-reported PA volume and intensity: low activity < 30 min/day of moderate-intensity activity (n = 11), moderately active ≥ 30 min/day of moderate-intensity PA (n = 10), and very active ≥ 60 min/day of PA at high intensity (n = 10). Participants completed an oral glucose tolerance test (50 g glucose) with capillary blood samples obtained at baseline, 15 min, 30 min, 45 min, 60 min, 90 min, and 120 min post-ingestion.ResultsThere were no significant differences between groups for age or body fat percentage or glycated hemoglobin (p > 0.05). The groups were significantly different in terms of baseline glucose level (p = 0.003) and, marginally, for gender (p = 0.053) and BMI (p = 0.050). There was a statistically significant effect of PA on the 1-h postprandial glucose results (p = 0.029), with differences between very active and low activity groups (p = 0.008) but not between the moderately active and low activity groups (p = 0.360), even when baseline glucose level and gender differences were accounted for. For incremental area under the curve there was no significant effect of activity group once gender and body fat percentage had been accounted for (p = 0.401). Those in the low activity group took 15 min longer to reach peak glucose level than those in the very active group (p = 0.012).ConclusionThe results suggest that high levels of PA have a beneficial effect on postprandial blood glucose profiles when compared to low and moderate levels of activity.     

Effects of latissimus dorsi length on shoulder flexion in canoeists,swimmers, rugby players,and controls

BackgroundShoulder flexion requires an optimal length of the latissimus dorsi muscle in order to allow full lateral rotation of the humerus and upward scapular rotation. If shoulder flexion (in an externally rotated position) is restricted, this may predispose the individual to shoulder pathology. Sports such as swimming and canoeing have increased shoulder injuries and require high levels of latissimus dorsi muscle activity, which may create muscle hypertrophy and increased stiffness, resulting in a loss of muscle length. The objective of this study was to investigate if differences are present in shoulder flexion in internally and externally rotated positions across different sports (swimming, canoeing, and rugby) and a non-sporting control group.MethodsOne hundred subjects (40 physically active controls, 25 professional Rugby Union players, 20 elite, national-level canoeists (slalom), and 15 elite, national-level swimmers) participated in this study. Shoulder flexion range of motion was measured using a standard goniometer, with the arm elevated in either full external or internal rotation.ResultsA significant difference in shoulder flexion range was observed between canoeists and swimmers, canoeists and controls, rugby players and canoeists, rugby players and swimmers, and controls and swimmers in the external rotation position (p < 0.017), but not between controls and rugby players (p = 0.12). For the internal rotation position, swimmers significantly differed from canoeists, rugby players, and controls (p < 0.017), but there were no significant differences between rugby players, canoeists, and controls (p > 0.07).ConclusionThis study found that the length of the latissimus dorsi differs between sports and controls in accordance with the specific physical demands of their sport.     

Effectiveness and time-course adaptation of resistance training vs. plyometric training in prepubertal soccer players

PurposeThis study aimed to assess the effectiveness and time course for improvements in explosive actions through resistance training (RT) vs. plyometric training (PT) in prepubertal soccer players.MethodsThirty-four male subjects were assigned to: a control group (n = 11); an RT group (5 regular soccer training sessions per week, n = 12); a PT group (3 soccer training sessions and 2 RT sessions per week, n = 11). The outcome measures included tests for the assessment of muscle strength (e.g., 1 repetition maximum half-squat test), jump ability (e.g., countermovement jump, squat jump, standing long jump, and multiple 5 bounds test), linear speed (e.g., 20 m sprint test), and change of direction (e.g., Illinois change of direction test).ResultsThe RTG showed an improvement in the half-squat (Δ = 13.2%; d = 1.3, p < 0.001) and countermovement jump (Δ = 9.4%; d = 2.4, p < 0.001) at Week 4, whereas improvements in the 20-m sprint (Δ = 4.2%; d = 1.1, p < 0.01); change of direction (CoD) (Δ = 3.8%; d = 2.1, p < 0.01); multiple 5 bounds (Δ = 5.1%; d = 1.5, p < 0.05); standing long jump (Δ = 7.2%; d = 1.2, p < 0.01); squat jump (Δ = 19.6%; d = 1.5, p < 0.01); were evident at Week 8. The PTG showed improvements in CoD (Δ = 2.1%; d = 1.3, p < 0.05); standing long jump (Δ = 9.3%; d = 1.1, p < 0.01); countermovement jump (Δ = 16.1%; d = 1.2, p < 0.01); and squat jump (Δ = 16.7%; d = 1.4, p < 0.01); at Week 8 whereas improvements in the 20-m sprint (Δ = 4.1%; d = 1.3, p < 0.01); and multiple 5 bounds (Δ = 7.4%; d = 2.4, p < 0.001); were evident only after Week. The RT and PT groups showed improvements in all sprint, CoD, and jump tests (p < 0.05) and in half-squat performance, for which improvement was only shown within the RTG (p < 0.001).ConclusionRT and PT conducted in combination with regular soccer training are safe and feasible interventions for prepubertal soccer players. In addition, these interventions were shown to be effective training tools to improve explosive actions with different time courses of improvements, which manifested earlier in the RTG than in the PTG. These outcomes may help coaches and fitness trainers set out clear and concise goals of training according to the specific time course of improvement difference between RT and PT on proxies of athletic performance of prepubertal soccer players.     

Non-linear resistance training reduces inflammatory biomarkers in persons living with HIV: A randomized controlled trial

The purpose of this study is to analyse the effect of 12 weeks of non-linear resistance training (NLRT) on anthropometry, muscle strength and inflammatory biomarkers in persons infected with human immunodeficiency virus (PIHIV). Thirty previously sedentary PIHIVs were randomized into the NLRT (n?=?15) and control (CON, n?=?15) groups. NLRT group were submitted to 12 weeks of training, whereas the CON group maintained their daily habits. At baseline and after 12 weeks, both groups underwent anthropometric evaluations and blood sampling for the analysis of inflammatory biomarkers. Analysis of covariance using preintervention values as covariate was performed to determine the effects of exercise on anthropometry, muscle strength, cytokines levels and T cells. Significance was set at p?p?p p?=?.009), blood levels of interleukin (IL)-1β (p?=?.029), IL-6 (p?=?.005), IL-8 (p?=?.010), and tumour necrosis factor (TNF)-α (p?=?.001) and an increase in muscle strength (p?p?=?.030) and CD4⁺ (p?=?.004) and CD8⁺ (p?相似文献   

Examining the intrinsic foot muscles’ capacity to modulate plantar flexor gearing and ankle joint contributions to propulsion in vertical jumping

BackgroundDuring human locomotion, a sufficiently stiff foot allows the ankle plantar flexors to generate large propulsive powers. Increasing foot stiffness (e.g., via a carbon plate) increases the ankle's external moment arm in relation to the internal moment arm (i.e., increasing gear ratio), reduces plantar flexor muscles’ shortening velocity, and enhances muscle force production. In contrast, when activation of the foot's intrinsic muscles is impaired, there is a reduction in foot and ankle work and metatarsophalangeal joint stiffness. We speculated that the reduced capacity to actively control metatarsophalangeal joint stiffness may impair the gearing function of the foot at the ankle.MethodsWe used a tibial nerve block to examine the direct effects of the intrinsic foot muscles on ankle joint kinetics, in vivo medial gastrocnemius’ musculotendinous dynamics, and ankle gear ratio on 14 participants during maximal vertical jumping.ResultsUnder the nerve block, the internal ankle plantar flexion moment decreased (p = 0.004) alongside a reduction in external moment arm length (p = 0.021) and ankle joint gear ratio (p = 0.049) when compared to the non-blocked condition. Although medial gastrocnemius muscle–tendon unit and fascicle velocity were not different between conditions, the Achilles tendon was shorter during propulsion in the nerve block condition (p < 0.001).ConclusionIn addition to their known role of regulating the energetic function of the foot, our data indicate that the intrinsic foot muscles also act to optimize ankle joint torque production and leverage during the propulsion phase of vertical jumping.     

Chronotropic incompetence is more frequent in obese adolescents and relates to systemic inflammation and exercise intolerance

BackgroundAdults with obesity may display disturbed cardiac chronotropic responses during cardiopulmonary exercise testing, which relates to poor cardiometabolic health and an increased risk for adverse cardiovascular events. It is unknown whether cardiac chronotropic incompetence (CI) during maximal exercise is already present in obese adolescents and, if so, how that relates to cardiometabolic health.MethodsSixty-nine obese adolescents (body mass index standard deviation score = 2.23 ± 0.32, age = 14.1 ± 1.2 years; mean ± SD) and 29 lean adolescents (body mass index standard deviation score = –0.16 ± 0.84, age = 14.0 ± 1.5 years) performed a maximal cardiopulmonary exercise testing from which indicators for peak performance were determined. The resting heart rate and peak heart rate were used to calculate the maximal chronotropic response index. Biochemistry (lipid profile, glycemic control, inflammation, and leptin) was studied in fasted blood samples and during an oral glucose tolerance test within obese adolescents. Regression analyses were applied to examine associations between the presence of CI and blood or exercise capacity parameters, respectively, within obese adolescents.ResultsCI was prevalent in 32 out of 69 obese adolescents (46%) and 3 out of 29 lean adolescents (10%). C-reactive protein was significantly higher in obese adolescents with CI compared to obese adolescents without CI (p = 0.012). Furthermore, peak oxygen uptake and peak cycling power output were significantly reduced (p < 0.05) in obese adolescents with CI vs. obese adolescents without CI. The chronotropic index was independently related to blood total cholesterol (standardized coefficient β = –0.332; p = 0.012) and C-reactive protein concentration (standardized coefficient β = –0.269; p = 0.039).ConclusionCI is more common in the current cohort of obese adolescents, and is related to systemic inflammation and exercise intolerance.     

Back to school after lockdown: The effect of COVID-19 restrictions on children's device-based physical activity metrics

BackgroundThe coronavirus disease-2019 (COVID-19) pandemic and national lockdowns took away opportunities for children to be physically active. This study aimed to determine the effect of the COVID-19 lockdown on accelerometer-assessed physical activity (PA) in children in Wales.MethodsEight hundred participants (8–18 years old), stratified by sex, age, and socio-economic status, wore Axivity AX3 accelerometers for 7 days in February 2021, during the lockdown, and in May 2021, while in school. Raw accelerometer data were processed in R-package GGIR, and cut-point data, average acceleration (AvAcc), intensity gradient, and the acceleration above which the most active X minutes are accumulated (MX) metrics were extracted. Linear mixed models were used to assess the influence of time-point, sex, age, and socioeconomic status (SES) on PA.ResultsDuring lockdown, moderate-to-vigorous PA was 38.4 ± 24.3 min/day; sedentary time was 849.4 ± 196.6 min/day; mean ± SD. PA levels increased significantly upon return to school (all variables p < 0.001). While there were no sex differences during lockdown (p = 0.233), girls engaged in significantly less moderate-to-vigorous PA than boys once back in school (p < 0.001). Furthermore, boys had more favorable intensity profiles than girls (intensity gradient: p < 0.001), regardless of time-point. PA levels decreased with age at both time-points; upper secondary school girls were the least active group, with an average M30 of 195.2 mg (while in school).ConclusionThe lockdown affected boys more than girls, as reflected by the disappearance of the typical sex difference in PA levels during lockdown, although these were re-established on return to school. Upper secondary school (especially girls) might need specific COVID-recovery intervention.     

Impact of an acute bout of vibration on muscle contractile properties,creatine kinase and lactate dehydrogenase response

Abstract

The aim of this study was to assess the effects of a bout of whole body vibration (WBV) on muscle response and to determine whether this stimulus leads to muscle damage. Thirty healthy and physically active participants (mean±SD; age: 21.8±2.0 years; height: 176.7±5.8 cm; body mass: 76±6.8 kg and BMI: 23.1±3.7 kg·m^?2) participated in this study. Participants were randomly allocated in one of two groups, one of them performed a bout of 360 s WBV (frequency: 30 Hz; peak-to-peak displacement: 4 mm) (VIB) and the other one adopted a sham position (CON). Muscle contractile properties were analysed in the rectus femoris (RF) by using tensiomyography (TMG) 2 min before the warm-up and 2 min after intervention. Muscle damage was assessed by determining plasma creatine kinase (CK) and lactate dehydrogenase (LDH) levels at three time points; 5 min before warm-up and 1 h and 48 h after the intervention. TMG results showed a significant decrease in maximal displacement (p<0.05) and delay time (p<0.05) in VIB and in delay time (p<0.05) and relaxation time (p<0.05) in CON. Muscle damage markers showed significant group differences (p<0.05) for CK 1 h after the intervention. In addition, differences for CK 1 h after the intervention from baseline (p<0.05) were also observed in VIB. In conclusion, a 6-min bout of WBV results in an increase of muscle stiffness in RF and increased CK levels 1 h after intervention (returning to baseline within 48 h).