This study investigated the changes in fascicle length (FL), musculotendinous unit (MTU) stiffness, muscle oxygen saturation (SmO2), and muscular performance following a single bout of a combination ...of static stretching (SS) or dynamic stretching (DS) with foam rolling (FR), SS only, and eccentric exercise (ECC) only in young men with hamstring tightness. Twenty-five men (20.5 ± 1.5 years) participated in a crossover randomized study of the four conditions (DS+FR, SS+FR, SS, and ECC); each session was spaced seven days apart. FL, MTU stiffness during the straight leg raise (SLR), hamstring SmO2, and isometric and eccentric torque were measured before, immediately and 30 min after exercise. Immediately after exercise, the SLR increased significantly by means of 7.4% (d = 1.07), 6% (d = 1.27), 6% (d = 1.10), and 8% (d = 1.04, all p < 0.001) for DS+FR, SS+FR, ECC, and SS, respectively. FL was longer after exercise under all four conditions (p < 0.05). MTU stiffness decreased after ECC (p = 0.038, d = 0.40). SmO2 tended to decrease for ECC (p > 0.05), but it was increased immediately after those three exercises. Hamstring isometric torque was significantly reduced by an average of 6–9%, but eccentric torque changes varied among conditions. In conclusion, substantial and similar immediate increases in hamstring flexibility, coupled with reduced isometric torque following various exercises, were accompanied by condition-specific alterations in fascicle length, MTU stiffness, or SmO2. These findings provide practical insights for acutely enhancing range of motion in individuals with tight hamstrings.
ABSTRACTVenckunas, T, Bruzas, V, Stasiulis, A, Snieckus, A, Mockus, P, and Kamandulis, S. Cardiorespiratory responses to specific and non-specific exercise in high-profile amateur boxers. J Strength ...Cond Res XX(X)000–000, 2020—Our aim was to compare cardiorespiratory responses in 3 types of all-out exercises (upper body, lower body, and punching) in well-trained boxers and peak heart rate (HR) in these tests with HR response to competitive Olympic boxing. On 4 separate occasions, 11 male amateur boxers performed(a) progressive treadmill running to exhaustion; (b) progressive arm cranking to failure; (c) progressive bag punching to maximal exertion; and (d) competitive boxing fight (3 × 3 minutes format). Expired gas and HR were measured in all tasks except in the full-contact competitive fight where only HR was recorded. Peak oxygen uptake (55.3 ± 5.9 ml·kg·min) was highest during treadmill running. Peak respiratory exchange ratio was highest during bag punching (1.26 ± 0.09), but did not differ between arm cranking and running. Peak HR of the boxing fight (197.7 ± 5.9 b·min) did not differ from that of running (196.5 ± 8.7 b·min), but was smaller in arm cranking (179.8 ± 9.2) and bag punching (184.1 ± 12.2 b·min). The correlation coefficients between peak HR achieved during competitive fighting and that achieved during running, arm cranking and bag punching were 0.720 (p = 0.013), 0.597 (p = 0.052), and 0.702 (p = 0.035), respectively. In conclusion, in high-profile amateur boxers, running evoked a higher cardiorespiratory activation than arm cranking or bag punching, whereas punching elicited the highest input of anaerobic glycolysis. Peak HR of competitive fighting was the same as during running and much higher than during arm cranking or bag punching.
While concurrent training is regularly used in older populations, the inverse relationship between fibre size and oxidative capacity suggests that endurance training in resistance-trained individuals ...may result in some loss of resistance training-induced gains in muscle mass, which may be more pronounced in older people. We investigated the impact of superimposed endurance training in younger (28.5 ± 4.8 years;
n
= 8) and older (67.5 ± 5.5 years;
n
= 7) highly resistance-trained men. Participants underwent a 10-week endurance cycling training programme consisting of five 6-min intervals at 75% max heart rate (HRmax) separated by 4-min intervals at 90% HRmax. The anatomical cross-sectional area (ACSA) of the thigh muscles, as determined with MRI, was 24% smaller in older compared to younger participants (
p
< 0.001). Although maximal oxygen consumption (VO
2
max) was also lower in the older group (
p
< 0.001), VO
2
max per kg body mass did not differ significantly between younger and older participants. Histological analyses of biopsies of the
m. vastus lateralis
showed that endurance training induced an increase in succinate dehydrogenase activity in both younger and older participants (
p
≤ 0.043), and an increase in the number of capillaries around type I fibres (
p
= 0.017). The superimposed endurance training did not induce a significant decrease in thigh ACSA, fibre cross-sectional area, or knee extensor maximum voluntary isometric force. These observations indicate that adding endurance training to resistance training can lead to positive endurance-related adaptations without negative consequences for muscle size and strength in older and younger resistance-trained people.
Purpose
Unaccustomed eccentric contractions generally result in a long-lasting contractile impairment, referred to as prolonged low-frequency force depression (PLFFD), and delayed-onset muscle ...soreness (DOMS). We here used repeated drop jumps (DJs) as an eccentric contraction model and studied the effects of increasing the time between DJs from 20 s to 5 min. We hypothesized that both PLFFD and DOMS would be less marked at the longer DJ interval due to the longer time to restore structural elements between DJs.
Methods
Young men (
n
= 12) randomly performed 50 DJs with either 20-s (DJ-20 s) or 5-min (DJ-5 min) rest between DJs. Voluntary, 20 Hz and 100 Hz electrically stimulated isometric knee extension torques and muscle soreness were monitored before and for 7 days after DJs; serum CK activity was measured to assess muscle fibre protein leakage. In additional experiments, changes in mRNA levels were assessed in muscle biopsies collected before and 1 h after exercise.
Results
A marked PLFFD was observed with both protocols and the extent of 20 Hz torque depression was smaller immediately and 1 day after DJ-5 min than after DJ-20 s (
p
< 0.05), whereas the MVC and 100 Hz torques were similarly decreased with the two protocols. Markedly larger differences between the two protocols were observed for the muscle soreness score, which 1–4 days after exercise was about two times larger with DJ-20 s than with DJ-5 min (
p
< 0.01).
Conclusions
The larger protective effect of the longer DJ interval against DOMS than against PLFFD indicates that their underlying mechanisms involve different structural elements.
Joint inflexibility is acknowledged as a significant contributor to functional limitations in the older adult, with lengthening-type exercises identified as a potential remedial approach. ...Nevertheless, the responses to eccentric exercise in female older adults have not been extensively studied especially in home-based environment. Here, we aimed to assess the effectiveness of home-based static stretching (ST), dynamic closed-chain stretching (DCS), or eccentric exercise (ECC) interventions on flexibility, musculotendinous architecture, and functional ability in healthy older women.
We randomly assigned 51 healthy older women (age 65.9 ± 3.4 years) to one of three interventional exercise groups: DCS (N = 17), ECC (N = 17), or ST (N = 17). The training was performed 3 times a week for 6 weeks. The participants’ musculotendinous stiffness, fascicle length, eccentric strength, and functional capacities were measured before the intervention, after 6 weeks of exercise, and at a 1-month follow-up.
The results showed that all three interventions improved hamstring flexibility and passive ankle dorsiflexion (p < 0.001), with increased biceps femoris and medial gastrocnemius fascicle length (p < 0.01). However, there was no significant change in musculotendinous stiffness. The ECC intervention produced a greater improvement in knee flexor and calf eccentric peak torque (p < 0.05), and gait speed (p = 0.024) than the other two interventions. The changes in flexibility and knee flexor strength remained for up to 4 weeks after detraining.
In conclusion, the present study suggests that home-based ECC may be more beneficial in enhancing physical capacities in older women compared with either DCS or SS interventions.
Purpose
To determine how muscle stiffness and pain which develop after eccentric exercise are affected by gentle stretching and repeated exercise.
Methods
Twenty-one healthy female participants ...undertook eccentric exercise of the elbow flexors and changes in resting elbow flexion angle (REFA; a measure of muscle stiffness), pain on stretch scale, pain elicited by pressure (PPT pain, a measure of mechanoreceptor hypersensitivity), and upper arm girth were followed for 7 days after exercise. The effects of gentle passive stretching on pain and muscle stiffness were investigated 2 and 4 days after exercise. Eleven participants also repeated the exercise with the same arm 6 weeks after the first bout.
Results
There was a significant relationship between the pain on stretch scale and increased REFA (day 4;
R
2
= 0.65,
p
< 0.001), whereas there was no relationship between REFA and PPT pain. REFA was reduced by passive stretching and pain on stretch scale was also reduced from 3.0 (1.4, 5.1) to 0.75 (0.0, 2.0) median (IQR),
p
= 0.01. PPT pain was unaffected by the passive stretching, as was muscle swelling. Following the repeated bout, increases in REFA were much reduced, as was pain on stretch scale (
p
= 0.02). However, PPT pain was not significantly different between the two bouts of exercise.
Conclusions
The results indicate that reductions in pain on stretch scale, either by gentle passive stretching or as the result of repeated exercise, are primarily due to reductions in muscle stiffness which develops after eccentric exercise, whereas mechanoreceptor hypersensitivity is relatively unaffected.
This study aimed to assess and compare the physiological percentage of maximal heart rate (%HR
), blood lactate (BLa), creatine kinase (CK), hormonal (testosterone, cortisol), psychological rating of ...perceived exertion (RPE), enjoyment and physical percentage of moderate-to-vigorous physical activity (%MVPA) and vigorous activity (%VA) responses of recreational 3 × 3 basketball (3 × 3BB) and high-intensity interval training (HIIT) in active young adults. Twelve apparently healthy male recreational basketball players (age: 23 ± 3 years; body mass: 82 ± 15 kg; stature: 188 ± 15 cm) completed a 3 × 3BB match and HIIT with similar duration. %HR
, %MVPA and %VA were monitored during the protocols, while BLa, cortisol, and testosterone were measured before and after each protocol. CK was measured before the protocols and at 24 h, while RPE and enjoyment were assessed at the end of each protocol. 3 × 3BB elicited higher %HR
(p < 0.001; d = -1.6, large), %MVPA (p < 0.001; d = 2.7, very large), %VA (p = 0.030; d = 0.8, moderate), enjoyment (p = 0.014; r-value = -0.500, large), and lower RPE (p = 0.024; r-value = -0.462, moderate) compared to the HIIT condition. Moreover, higher values of BLa were found in HIIT compared to 3 × 3BB at post-condition (p = 0.020; r-value = -0.601, large), while CK analysis showed only an increase within the HIIT condition (p = 0.020; r-value = -0.599, large). A time effect was found for both testosterone (p < 0.001, η
= 0.526, moderate) and cortisol (p = 0.005, η
= 0.743, strong), while no between-condition effect or interaction was found (p > 0.05). 3 × 3BB elicits higher %HR
, enjoyment, and physical activity intensities but lower BLa and RPE compared to HIIT in active young adults and might be considered as a potentially suitable activity to increase participants' health status.
Purpose
The purpose of this study was to compare the benefits and possible problems of 4 weeks stretching when taken to the point of pain (POP) and to the point of discomfort (POD).
Methods
...Twenty-six physically active women (20 ± 1.1 years) took part in group-based stretching classes of the hamstring muscles, 4 times per week for 4 weeks, one group one stretching to POD, the other to POP. Passive stiffness, joint range of motion (ROM), maximal isometric torque and concentric knee flexion torque, were measured before training and 2 days after the last training session.
Results
Hip flexion ROM increased by 14.1° (10.1°–18.1°) and 19.8° (15.1°–24.5°) and sit-and-reach by 7.6 (5.2–10.0) cm and 7.5 (5.0–10.0) cm for POD and POP, respectively (Mean and 95% CI;
p
< 0.001 within group;
NS
between groups), with no evidence of damage in either group. Despite the large increases in flexibility there were no changes in either compliance or viscoelastic properties of the muscle tendon unit (MTU).
Conclusion
Hamstrings stretching to POP increased flexibility and had no detrimental effects on muscle function but the benefits were no better than when stretching to POD so there is no justification for recommending painful stretching. The improvements in flexibility over 4 weeks of stretching training appear to be largely due to changes in the perception of pain rather than physical properties of the MTU although less flexible individuals benefited more from the training and increased hamstring muscle length.
Background:
Explosive and fast body movements, sprints, jumps and quick changes of direction, which are characteristic of the football training, place considerable strain on the hamstring muscles. ...Due to the high occurrence of hamstring injuries, new preventive strategies are required that focus on high-velocity training. The purpose was to assess the effectiveness of high-velocity elastic-band training in reducing the occurrence of hamstring injuries in football players.
Methods:
Male football players from 15 teams (n = 319) playing in national competitions participated in this study. The players were involved in a 5-week exercise period in either the intervention group (INT) or the control group (CON), with a follow-up period of ∼4 months where hamstring injuries and exposure time were recorded. The INT group had two to three sessions per week of elastic-band training with low-load, high-velocity leg curls while lying prone; the CON group performed self-paced football-specific drills.
Results:
The incidence rate of hamstring injuries was 6.5% in the INT group (8 out of 123 players) and 9.2% in the CON group (18 out of 196 players). Although the INT group showed almost 1/3 reduction in hamstring injury incidence compared to the CON group, the difference was not statistically significant (
p
> 0.05). Moreover, no differences (
p
> 0.05, odds ratio OR = trivial-to-small) in distribution between the groups were found in hamstring injury characteristics (leg dominance and mechanism) except for the distribution of injuries that occurred during matches or training (
p
= 0.036; OR = 6.14, moderate).
Conclusion:
The program of high-velocity elastic-band training did not prove to be effective in preventing hamstring muscle injuries in football players despite displaying some positive indications that could be considering when creating injury prevention programs.
ABSTRACTVenckunas, T, Snieckus, A, Trinkunas, E, Baranauskiene, N, Solianik, R, Juodsnukis, A, Streckis, V, and Kamandulis, S. Interval running training improves cognitive flexibility and aerobic ...power of young healthy adults. J Strength Cond Res 30(8)2114–2121, 2016—The benefits of regular physical exercise may well extend beyond the reduction of chronic diseases risk and augmentation of working capacity, to many other aspects of human well-being, including improved cognitive functioning. Although the effects of moderate intensity continuous training on cognitive performance are relatively well studied, the benefits of interval training have not been investigated in this respect so far. The aim of the current study was to assess whether 7 weeks of interval running training is effective at improving both aerobic fitness and cognitive performance. For this purpose, 8 young dinghy sailors (6 boys and 2 girls) completed the interval running program with 200 m and 2,000 m running performance, cycling maximal oxygen uptake, and cognitive function was measured before and after the intervention. The control group consisted of healthy age-matched subjects (8 boys and 2 girls) who continued their active lifestyle and were tested in the same way as the experimental group, but did not complete any regular training. In the experimental group, 200 m and 2,000 m running performance and cycling maximal oxygen uptake increased together with improved results on cognitive flexibility tasks. No changes in the results of short-term and working memory tasks were observed in the experimental group, and no changes in any of the measured indices were evident in the controls. In conclusion, 7 weeks of interval running training improved running performance and cycling aerobic power, and were sufficient to improve the ability to adjust behavior to changing demands in young active individuals.
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