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1.
ObjectiveResearch on methods of improving the affective experience of exercise remains limited, especially for low-active overweight adults. We investigated the effectiveness of a virtual-reality headset and headphones in improving affective responses over conventionally delivered audiovisual stimulation.MethodsLow-active, overweight adults (16 women, 5 men; age: 34.67 ± 9.62 years; body mass index: 28.56 ± 4.95 kg/m²; peak oxygen uptake for men: 29.14 ± 6.56 mL/kg/min, for women: 22.67 ± 4.52 mL/kg/min, mean ± SD) completed 15-min sessions of recumbent cycling at the ventilatory threshold: (a) high immersion (HI, virtual reality headset and headphones), (b) low immersion (LI, television screen and speakers), and (c) Control. During-exercise pleasure and post-exercise enjoyment were self-reported. Oxygenation of the right dorsolateral prefrontal cortex (dlPFC) was assessed with near infrared spectroscopy.ResultsHigher pleasure was reported during HI than during LI and Control (Condition × Time interaction; p < 0.001, ηp2 = 0.43). Participants who reported a preference for low exercise intensity showed higher dlPFC oxygenation during Control, but this difference diminished during LI and HI (Condition × Time × Preference interaction; p = 0.036, ηp2 = 0.10).ConclusionCompared with conventionally delivered audiovisual stimulation, using a virtual-reality headset strengthens the dissociative effect, further improving affective responses to exercise at the ventilatory threshold among overweight, low-active adults. Presumably by competing with interoceptive afferents at the level of sensory input, audiovisual stimulation may lessen reliance on cognitive efforts to attenuate declining affect, as indicated by lower right dlPFC activity, particularly among participants disinclined toward high exercise intensity.  相似文献   

2.
BackgroundAnkle complex proprioceptive ability, needed in active human movement, may change from childhood to elderly adulthood; however, its development across all life stages has remained unexamined. The aim of the present study was to investigate the across-the-lifespan trend for proprioceptive ability of the ankle complex during active ankle inversion movement.MethodsThe right ankles of 118 healthy right-handed participants in 6 groups were assessed: children (6–8 years old), adolescents (13–15 years old), young adults (18–25 years old), middle-aged adults (35–50 years old), old adults (60–74 years old), and very old adults (75–90 years old). While the participants were standing, their ankle complex proprioception was measured using the Active Movement Extent Discrimination Apparatus.ResultsThere was no significant interaction between the effects of age group and gender on ankle proprioceptive acuity (F (5, 106) = 0.593, p = 0.705, η2p = 0.027). Simple main effects analysis showed that there was a significant main effect for age group (F (5, 106) = 22.521, p < 0.001, η2p = 0.515) but no significant main effect for gender (F (1,106) = 2.283, p = 0.134, η2p = 0.021) between the female (0.723 ± 0.092, mean ± SD) and the male (0.712 ± 0.083) participants. The age-group factor was associated with a significant linear downward trend in scores (F (1, 106) = 10.584, p = 0.002, η2p = 0.091) and a strong quadratic trend component (F (1,106) = 100.701, p < 0.001, η2p = 0.480), producing an asymmetric inverted-U function.ConclusionThe test method of the Active Movement Extent Discrimination Apparatus is sensitive to age differences in ankle complex proprioception. For proprioception of the ankle complex, young adults had significantly better scores than children, adolescents, old adults, and very old adults. The middle-aged group had levels of ankle proprioceptive acuity similar to those of the young adults. The scores for males and females were not significantly different. Examination of the range of the scores in each age group highlights the possible level that ankle complex movement proprioceptive rehabilitation can reach, especially for those 75–90 years of age.  相似文献   

3.
ABSTRACT

Hamstring strain injury (HSI) rates are higher for males vs. females. This cross-sectional study investigated if inherent differences in biceps femoris long head (BFLH) fascicle length (Lf) exist between recreationally active males and females (i.e., individuals without specific training practice history). Twenty-four young healthy participants (12 males; 12 females) had their BFLH muscle architecture (Lf, pennation angle [θp], and muscle thickness [MT]) measured using B-mode ultrasonography. Eccentric and isometric knee flexion strength were also assessed. BFLH Lf did not differ between sexes when expressed in absolute terms (males, 81.5 ± 14.7 mm; females, 73.6 ± 15.9 mm, P = 0.220, effect size (ES) = 0.52) or relative to femur length (0.140 ≤ P ≤ 0.220, ES = 0.63). Similarly, BFLH θp did not differ between sexes (P = 0.650) but BFLH MT was 18.9% larger for males vs. females (P = 0.024, ES = 0.99). Isometric and eccentric knee flexion strength was greater for males vs. females in absolute terms ([both] P < 0.001, 2.00 ≤ ES ≤ 2.27) and relative to body mass ([both] P < 0.001, 1.93 ≤ ES ≤ 2.13). In conclusion, factors other than BFLH Lf seem likely to be implicated in higher male vs. female HSI rates.  相似文献   

4.
PurposeThe present study investigated the effects of 16 weeks of small-volume, small-sided soccer training soccer group (SG, n = 13) and oscillating whole-body vibration training vibration group (VG, n = 17) on body composition, aerobic fitness, and muscle PCr kinetics in healthy inactive premenopausal women in comparison with an inactive control group (CO, n = 14).MethodsTraining for SG and VG consisted of twice-weekly 15-min sessions with average heart rates (HRs) of ∼155 and 90 bpm respectively. Pre- and post-measurements of body composition (DXA), phosphocreatine (PCr) on- and off-kinetics, and HR measurements during standardised submaximal exercise were performed.ResultsAfter 16 weeks of training in SG, fat percentage was lowered (p = 0.03) by 1.7% ± 2.4% from 37.5% ± 6.9% to 35.8% ± 6.2% and the PCr decrease in the quadriceps during knee-extension ramp exercise was attenuated (4% ± 8%, p = 0.04), with no changes in VG or CO (time-group effect: p = 0.03 and p = 0.03). Submaximal exercise HR was also reduced in SG after 16 weeks of training (6% ± 5% of HRmax, p = 0.01).ConclusionShort duration soccer training for 16 weeks appears to be sufficient to induce favourable changes in body composition and indicators of aerobic fitness and muscle oxidative capacity in untrained premenopausal women.  相似文献   

5.
This study aims to (1) determine whether isometric training at a short vs. long quadriceps muscle length affects concentric torque production; (2) examine the relationship between muscle hypertrophy and concentric torque; and (3) determine whether changes in fascicle length are associated with changes in concentric torque.

Sixteen men performed isometric training at a short (SL, n = 8) or a long muscle length (LL, n = 8). Changes in maximal concentric torque were measured at 30, 60, 90, 120, 180, 240 and 300 rad · s?1. The relationships between the changes in concentric torque, cross-sectional area, volume and fascicle length were tested.

Concentric torque increased significantly after training only in LL and at angular velocities of 30 and 120 rad · s?1 by 12–13% (P < 0.05). Muscle size increased in LL only, the changes were correlated (r = 0.73–0.93, P < 0.05) with the changes in concentric torque. Vastus lateralis (VL) fascicle length increased in both groups (5.4 ± 4.9%, P = 0.001) but the change was not correlated with changes in concentric torque in either group.

Isometric training-induced increases in muscle size and concentric torque were best elicited by training at long muscle lengths. These results highlight a clear muscle length dependence of isometric training on dynamic torque production.  相似文献   

6.
Background:Public health guidelines have called for innovative and flexible physical activity(PA)intervention strategies to promote PA and health amid the coronavirus disease 2019(COVID-19)pandemic.Therefore,this study’s purpose was to examine the effects of a home-based,YouTube-delivered PA intervention grounded in self-determination theory on young adults’free-living PA,sedentary behavior,and sleep quality(NCT04499547).Methods:Sixty-four young adults(48 females;age=22.8±3.4 years,mean±SD;body mass index=23.1±2.6 kg/m2)were randomized(1:1)into the intervention group,which received weekly aerobic and muscle-strengthening PA videos,or control group,which received weekly general health education videos,for 12 weeks.Our primary outcome was free-living moderate-to-vigorous PA(MVPA)and our secondary outcomes were sedentary behavior,light PA,and sleep quality(measured using ActiGraph accelerometers)along with muscle-strengthening PA frequency,self-determination theory-related motivation(non-regulation,external regulation,introjected regulation,identified regulation,integrated regulation,and intrinsic regulation),and perceived PA barriers(assessed using validated questionnaires).Repeated measures analysis of variances(ANOVAs)examined between-group differences at an adjusted significance level of 0.004 and effect sizes as partial eta-squared(η;).Results:We observed statistically significant interaction effects for MVPA,sleep efficiency,muscle-strengthening PA frequency,non-regulation,integrated regulation,intrinsic regulation,and perceived PA barriers(F(1,62)=10.75-77.67,p<0.001-0.002,ηp2=0.15-0.56)with all outcomes favoring the intervention group.We observed no statistically significant differences in either group for sedentary behavior,light PA,sleep duration,or external,introjected,and identified regulations after 12 weeks(F(1,62)=1.11-3.64,p=0.06-0.61).Conclusion:With national COVID-19 restrictions still in place and uncertainty regarding post-pandemic PA environments and behaviors,a remote,YouTube-delivered PA intervention may help foster clinically meaningful improvements in young adults’free-living MVPA,musclestrengthening PA frequency,sleep efficiency,PA-related intrinsic motivation,and perceived PA barriers.  相似文献   

7.
ABSTRACT

In this study, we aimed to clarify the characteristics of neuromuscular function, kinetics, and kinematics of the lower extremity during sprinting in track and field athletes with a history of strain injury. Ten male college sprinters with a history of unilateral hamstring injury performed maximum effort sprint on an athletic track. The electromyographic (EMG) activity of the long head of the biceps femoris (BFlh) and gluteus maximus (Gmax) muscles and three-dimensional kinematic data were recorded. Bilateral comparisons were performed for the EMG activities, pelvic anterior tilt angle, hip and knee joint angles and torques, and the musculotendon length of BFlh. The activity of BFlh in the previously injured limb was significantly lower than that in the uninjured limb during the late-swing phase of sprinting (p < 0.05). However, the EMG activity of Gmax was not significantly different between the previously injured and uninjured limbs. Furthermore, during the late-swing phase, a significantly more flexed knee angle (p < 0.05) and a decrease in BFlh muscle length (p < 0.05) were noted in the injured limb. It was concluded that previously injured hamstring muscles demonstrate functional deficits during the late swing phase of sprinting in comparison with the uninjured contralateral muscles.  相似文献   

8.
Purpose: The purpose of this study was to compare the kicking performance of young soccer players in the U9 to U20 age groups. Method: Three hundred and sixty-six Brazilian players were evaluated on an official pitch using three-dimensional kinematics to measure (300 Hz) ball velocity (Vball), foot velocity (Vfoot), Vball/Vfoot ratio, last stride length, and distance between the support foot and the ball. Simultaneously, a two-dimensional procedure was also conducted to compute (60 Hz) the mean radial error, bivariate variable error, and accuracy. Possible age-related differences were assessed through one-way analysis of variance and magnitude-based inferences. Results: Ball velocity increased by 103% (p < .001, η2 = .39) from the U11 age group (48.54 ± 8.31 km/hr) to the U20 age group (98.74 ± 16.35 km/hr). Foot velocity presented a 59% increase (p < .001, η2 = .32) from the U11 age group (49.08 ± 5.16 km/hr) to U20 (78.24 ± 9.49 km/hr). This finding was due to improvement in the quality of foot–ball impact (Vball/Vfoot ratio) from U11 (0.99 ± 0.13 a.u.) to U20 (1.26 ± 0.11 a.u.; p < .001, η2 = .25). Parameters such as mean radial error and accuracy appeared to be impaired during the growth spurt (U13–U15). Last stride length was correlated, low to moderately high, with Vball in all age groups (r = .36–.79). Conclusions: In summary, we concluded that simple biomechanical parameters of kicking performance presented distinct development. These results suggest that different training strategies specific for each age group could be applied. We provide predictive equations to aid coaches in the long-term monitoring process to develop the kick in soccer or search for talented young players.  相似文献   

9.
BackgroundIt remains unclear whether studies comparing maximal oxygen uptake (VO2max) response to sprint interval training (SIT) vs. moderate-intensity continuous training (MICT) are associated with a high risk of bias and poor reporting quality. The purpose of this study was to evaluate the risk of bias and quality of reporting in studies comparing changes in VO2max between SIT and MICT.MethodsWe conducted a comprehensive literature search of 4 major databases: AMED, CINAHL, EMBASE, and MEDLINE. Studies were excluded if participants were not healthy adult humans or if training protocols were unsupervised, lasted less than 2 weeks, or utilized mixed exercise modalities. We used the Cochrane Collaboration tool and the CONSORT checklist for non-pharmacological trials to evaluate the risk of bias and reporting quality, respectively.ResultsTwenty-eight studies with 30 comparisons (3 studies included 2 SIT groups) were included in our meta-analysis (n = 360 SIT participants: body mass index (BMI) = 25.9 ± 3.7 kg/m2, baseline VO2max = 37.9 ± 8.0 mL/kg/min; n = 359 MICT participants: BMI = 25.5 ± 3.8 kg/m2, baseline VO2max = 38.3 ± 8.0 mL/kg/min; all mean ± SD). All studies had an unclear risk of bias and poor reporting quality.ConclusionAlthough we observed a lack of superiority between SIT and MICT for improving VO2max (weighted Hedge's g = ?0.004, 95% confidence interval (95%CI): ?0.08 to 0.07), the overall unclear risk of bias calls the validity of this conclusion into question. Future studies using robust study designs are needed to interrogate the possibility that SIT and MICT result in similar changes in VO2max.  相似文献   

10.
Purpose: This study investigated the physiological effects of wearing a mouthguard during submaximal treadmill exercise. Method: Twenty-four recreationally active males (Mage = 21.3 ± 2.4 years, Mheight = 1.78 ± 0.06 m, Mweight = 81.9 ± 10.6 kg, Mbody mass index = 25.8 ± 3.4 kg·m?2) performed incremental, continuous exercise at 2, 4, 6, and 8 mph (3.2, 6.4, 9.7, 12.9 kph) for 5 min at each speed on a motor-driven treadmill on 2 separate occasions in a randomized, crossover, counterbalanced design while wearing or not wearing a self-adaptable “boil and bite” mouthguard. Respiratory rate (RR), tidal volume (VT), ventilation (VE), oxygen consumption (VO2), respiratory exchange ratio (RER), and heart rate (HR) data were averaged during the last 60 s of each exercise stage; blood lactate (LA) was measured before exercise and 3 min and 10 min following exercise. Results: Repeated-measures analysis of variance revealed that mouthguard use failed to alter the response of RR, VT, VE, VO2, RER, and HR to treadmill exercise (p > .05), although each variable did increase in magnitude as a result of increasing treadmill speed (p < .001). Although increasing to above resting values at both 3 min and 10 min (p < .001) after cessation of exercise, LA levels also displayed no differences with mouthguard use (p > .05). Conclusion: Despite predictable increases in respiratory, metabolic, and cardiovascular variables in response to incremental exercise, the presence of a mouthguard failed to affect the magnitude or nature of these physiological responses.  相似文献   

11.
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.  相似文献   

12.
This study compared knee angle-specific neuromuscular adaptations after two low-volume isometric leg press complex training programmes performed at different muscle lengths. Fifteen young males were divided into two groups and trained three times per week for 6 weeks. One group (n?=?8) performed 5–7 sets of 3 s maximum isometric leg press exercise, with 4?min recovery, with knee angle at 85°?±?2° (longer muscle-tendon unit length; L-MTU). The other group (n?=?7) performed the same isometric training at a knee angle of 145°?±?2° (180°?=?full extension; shorter muscle-tendon unit length; S-MTU). During the recovery after each set of isometric exercise, participants performed two CMJ every minute, as a form of complex training. Maximum isometric force (MIF) and rate of force development (RFD) were measured over a wide range of knee angles. Countermovement jump (CMJ) performance and maximum half-squat strength (1RM) were also assessed. Training at S-MTU induced a large increase of MIF (22–58%, p?p?p?=?0.001). In contrast, training at L-MTU, resulted in a moderate and similar (≈12.3%, p?=?0.028) improvement of force at all knee angles. CMJ performance and 1RM were equally increased in both groups after training by 10.4%?±?8.3% and 7.8%?±?4.7% (p?相似文献   

13.
BackgroundPoor sleep quality is associated with adverse effects on health outcomes. It is not clear whether exercise can improve sleep quality and whether intensity of exercise affects any of the effects.MethodsFifteen healthy, non-obese (body mass index = 24.4 ± 2.1 kg/m2, mean ± SD), sedentary (<20 min of exercise on no more than 3 times/week) older women (66.1 ± 3.9 years) volunteered for the study. Peak oxygen consumption (VO2peak) was evaluated using a graded exercise test on a treadmill with a metabolic cart. Following a 7-day baseline period, each participant completed two exercise sessions (separated by 1 week) with equal caloric expenditure, but at different intensities (60% and 45% VO2peak, sequence randomized) between 9:00 and 11:00 am. A wrist ActiGraph monitor was used to assess sleep at baseline and two nights following each exercise session.ResultsThe average duration of the exercise was 54 and 72 min, respectively at 60% (moderate-intensity) and 45% VO2peak (light-intensity). Wake time after sleep onset was significantly shorter (p = 0.016), the number of awakenings was less (p = 0.046), and total activity counts were lower (p = 0.05) after the moderate-intensity exercise compared to baseline no-exercise condition.ConclusionOur data showed that a single moderate-intensity aerobic exercise session improved sleep quality in older women.  相似文献   

14.
BackgroundThere is controversial evidence regarding the effect of acute resistance exercise (ARE) on heart rate variability (HRV) parameters, which indicates the activities of the cardiac autonomic nervous system. The aim of this study was to perform a systematic review and meta-analysis of the literature on the effect of ARE on HRV parameters and identify its possible moderating factors.MethodsThe PubMed–Medline, Web of Science, SPORTDiscus, and Cochrane Library databases were searched. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) declaration was followed, and the methodological quality of the studies was evaluated. The level of significance was set at p ≤ 0.05. Twenty-six studies met the inclusion criteria. Main effect analyses between pre- and post-test interventions demonstrated an increase in normalized units low frequency (p < 0.001; standardized mean difference (SMD) = 0.78; 95% confidence interval (95%CI): 0.46?1.11) and low frequency/high frequency ratio (p < 0.001; SMD = 0.82; 95%CI: 0.64?0.99) and a decrease in standard deviation of the normal-to-normal (NN) interval (p < 0.001; SMD = –0.58; 95%CI: –0.85 to –0.30), root mean square of the successive differences (p < 0.001; SMD = –1.01; 95%CI: –1.29 to –0.74), and normalized units high frequency (p < 0.001; SMD: –1.08; 95%CI: –1.43 to –0.73) following ARE in healthy individuals range: 15 ± 1 to 48 ± 2 years; mean ± SD).ResultsThere were differences between the subgroups in the number of sets used in an exercise (p = 0.05) for root mean square of the successive differences, as well as for exercise intensity (p = 0.01) and rest between sets (p = 0.05) for normalized units high frequency. Interestingly, there were differences between the subgroups in training volume for root mean square of the successive differences (p = 0.01), normalized units high frequency (p = 0.003) and normalized units low frequency (p = 0.02).ConclusionOverall, there was a withdrawal of cardiac parasympathetic and activation of cardiac sympathetic modulations following ARE, and these changes were greater with higher training volume ～30 min after ARE in healthy individuals. Furthermore, the number of sets, intensity, and rest between sets affected HRV parameters. However, gender, body mass index, and training status did not influence the changes in HRV parameters as a response to ARE.  相似文献   

15.
BackgroundHigh-intensity interval training (HIIT) induces similar or even superior adaptations compared to continuous endurance training. Indeed, just 6 HIIT sessions over 2 weeks significantly improves maximal oxygen uptake (VO2max), submaximal exercise fat oxidation, and endurance performance. Whether even faster adaptations can be achieved with HIIT is not known. Thus, we aimed to determine whether 2 sessions of HIIT per day, separated by 3 h, every other day for 5 days (double HIIT (HIIT-D), n = 15) could increase VO2max, submaximal exercise fat oxidation, and endurance capacity as effectively as 6 sessions of HIIT over 2 weeks (single HIIT (HIIT-S), n = 13).MethodsEach training session consisted of 10 × 60 s of cycling at 100% of VO2max interspersed with 75 s of low-intensity cycling at 60 watt (W). Pre- and post-training assessments included VO2max, time to exhaustion at ∼80% of VO2max, and 60-min cycling trials at ∼67% of VO2max.ResultsSimilar increases (p < 0.05) in VO2max (HIIT-D: 7.7% vs. HIIT-S: 6.0%, p > 0.05) and endurance capacity (HIIT-D: 80.1% vs. HIIT-S: 79.2%, p > 0.05) were observed. Submaximal exercise carbohydrate oxidation was reduced in the 2 groups after exercise training (HIIT-D: 9.2%, p = 0.014 vs. HIIT-S: 18.8%, p = 0.012) while submaximal exercise fat oxidation was significantly increased in HIIT-D (15.5%, p = 0.048) but not in HIIT-S (9.3%, p = 0.290).ConclusionSix HIIT sessions over 5 days was as effective in increasing VO2max and endurance capacity and was more effective in improving submaximal exercise fat oxidation than 6 HIIT sessions over 2 weeks.  相似文献   

16.
The aims of this study were to assess changes in muscle architecture, isometric and dynamic strength of the leg extensor muscles, resulting from dynamic resistance training, and the relationships between strength and muscle architecture variables. The participants (n = 30) were randomly assigned to one of two groups. The training group (n = 16; age 21.8 +/- 2.3 years, body mass 74.8 +/- 9.2 kg, height 1.75 +/- 0.08 m) performed dynamic resistance training for 13 weeks. The control group (n = 14; age 19.9 +/- 1.5 years, body mass 74.0 +/- 8.5 kg, height 1.76 +/- 0.05 m) did not perform any resistance training. Maximal dynamic and isometric strength were tested in both groups, before and after the training period. The members of the training group used the free-weight squat lift (90 degrees ) as their training exercise. The concentric phase of the squat was performed explosively. Skeletal muscle architecture of the vastus lateralis was visualized using ultrasonography. At the end of the study, significant increases in vastus lateralis muscle thickness (+6.9%, P < 0.001), fascicle length (+10.3%, P < 0.05), one-repetition maximum (+8.2%, P < 0.05), rate of force development (+23.8%, P < 0.05) and average force produced in the first 500 ms (+11.7%, P < 0.05) were seen only in the training group. Adaptations to the muscle architecture in the training group limited the loss of fibre force, and improved the capacity for developing higher velocities of contraction. The architectural changes in the training group were similar to those seen in studies where high-speed training was performed. In conclusion, dynamic resistance training with light loads leads to increases in muscle thickness and fascicle length, which might be related to a more efficient transmission of fibre force to the tendon.  相似文献   

17.
ABSTRACT

The optimal scheduling of Nordic Hamstring exercises (NHEs) relative to football training sessions is unknown. We examined the acute neuromuscular and performance responses to NHE undertaken either before (BT) or after (AT) simulated football training. Twelve amateur players performed six sets of five repetitions of the NHE either before or after 60 min of standardised football-specific exercise (SAFT60). Surface electromyography signals (EMG) of the hamstring muscles were recorded during both the NHE, and maximum eccentric actions of the knee flexors (0.52 rad · s–1) performed before and after the NHE programme, and at 15 min intervals during SAFT60. Ten-metre sprint times were recorded on three occasions during each 15 min SAFT60 segment. Greater eccentric hamstring fatigue following the NHE programme was observed in BT versus AT (19.8 %; very likely small effect), which was particularly apparent in the latter range of knee flexion (0–15°; 39.6%; likely moderate effect), and synonymous with hamstring EMG declines (likely small–likely moderate effects). Performing NHE BT attenuated sprint performance declines (2.0–3.2%; likely small effects), but decreased eccentric hamstring peak torque (–14.1 to –18.9%; likely small effects) during football-specific exercise. Performing NHE prior to football training reduces eccentric hamstring strength and may exacerbate hamstring injury risk.  相似文献   

18.
The present experiment sought to further understanding of the effects of personalised audiovisual stimuli on psychological and psychophysiological responses during exercise in adults with obesity. Twenty-four participants (Mage = 28.3, SD = 5.5 years; MBMI = 32.2, SD = 2.4) engaged in self-paced exercises on a recumbent cycle ergometer and three conditions (sensory stimulation [ST], sensory deprivation [DE], and control [CO]) were administered. Perceptual (attentional focus and perceived exertion), affective (affective state and perceived activation), and psychophysiological (heart rate variability) parameters were monitored throughout the exercise bouts. A one-way repeated measures analysis of variance was used to compare self-reported and psychophysiological variables (main and interaction effects [5 Timepoints × 3 Conditions]). The results indicate that ST increased the use of dissociative thoughts throughout the exercise session (ηp2 = .19), ameliorated fatigue-related symptoms (ηp2 = .15) and elicited more positive affective responses (ηp2 = .12) than CO and DE. Accordingly, personally-compiled videos are highly effective in ameliorating exertional responses and enhancing affective valence during self-paced exercise in adults with obesity. Audiovisual stimuli could be used during the most critical periods of the exercise regimen (e.g., first training sessions) when individuals with obesity are more likely to focus on fatigue-related sensations.  相似文献   

19.
BackgroundLow levels of antioxidant paraoxonase 1 (PON1) enzyme activity, PON1–Q192R polymorphism (a glutamine (Q) to arginine (R) substitution at position 192), PON1–L55M polymorphism (a leucine (L) to methionine (M) substitution at position 55), and oxidized low-density lipoprotein (oxLDL) are risk factors for coronary heart disease. Aerobic exercise improves PON1 activity, but the effects of hypoxic exercise are yet unclear. The aim of this study was to determine the effects of hypoxic underwater rugby training on PON1 activity and oxLDL levels and the role of the mentioned polymorphisms.MethodsSerum PON1 and arylesterase activities (ARE), PON1, PON3, and oxLDL protein levels (by using the enzyme-linked immunosorbent assays) were determined in an athletic group (42 trained male underwater rugby players; age = 21.7 ± 4.2 years, mean ± SD) and a control group (43 sedentary men; age = 23.9 ± 3.2 years). The polymorphisms were determined from genomic DNA samples.ResultsPON1 activity (25.1%, p = 0.052), PON3 (p < 0.001), and oxLDL (p < 0.001) of the athletic group, including most genotype groups, were higher than those of the control group. In comparison to the controls, PON1 activity levels (p = 0.005) of the PON1–Q192R homozygote QQ genotype group and PON1 activity levels (30%, p = 0.116) of the PON1–L55M homozygote LL genotype group were higher, whereas ARE activity values of athletic R allele carrier (Rc = QR + RR) (p = 0.005) and LL group (p = 0.002) were lower than the control genotype groups related to their polymorphisms.ConclusionHypoxic training can cause (1) significant oxidative stress, including oxLDL, and an antioxidant response (increase in PON1 activity and PON3), (2) differences in the activity of PON1 and ARE, which are modified by PON1–Q192R and PON1–L55M polymorphisms, respectively, and (3) improvements in PON1 activity of QQ and LL groups. However, hypoxic training can cause a disadvantage of LL and Rc groups for ARE.  相似文献   

20.
ABSTRACT

We examined the association between footfall pattern and characteristics of lower limb muscle function and compared lower limb muscle function between forefoot and rearfoot runners. Fifteen rearfoot and 16 forefoot runners were evaluated using ultrasonography of the gastrocnemii and tibialis anterior while strike index and heel strike angle quantified footfall pattern. Higher strike index was associated with lower medial gastrocnemius echo intensity (p = 0.05), lower lateral gastrocnemius echo intensity (p = 0.04), smaller tibialis anterior pennation angle (p = 0.05), and longer lateral gastrocnemius fascicle length (p = 0.04). Larger heel strike angle was associated with smaller medial gastrocnemius cross-sectional area (p = 0.04), shorter lateral gastrocnemius fascicle length (p < 0.01), and lower plantar flexion moment (p < 0.01). Larger plantar flexion moment was associated with lesser medial gastrocnemius echo intensity (p = 0.04), lesser lateral gastrocnemius echo intensity (p = 0.03), and greater lateral gastrocnemius fascicle length (p = 0.02). A smaller plantar flexion moment, larger heel strike angle, lower tibialis anterior echo intensity, larger tibialis anterior pennation angle, and smaller lateral gastrocnemius pennation angle were observed in rearfoot compared to forefoot runners (p < 0.05). Lower limb muscle architecture is associated with footfall pattern and ankle mechanics during running.

Abbreviation: EMG: electromyographic; MG: medial gastrocnemius; LG: lateral gastrocnemius; TA: tibialis anterior; EI: echo intensity; CSA: cross-sectional area; PA: pennation angle; FL: fascicle length; FT: fat thickness  相似文献   

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