Minimum Intensity of Daily Six Eccentric Contractions to Increase Muscle Strength and Size.

Our previous study showed that daily six maximal eccentric contractions that were performed 5 days a week for 4 weeks increased maximal voluntary isometric (MVC-ISO), concentric (MVC-CON), and eccentric contraction (MVC-ECC) strength of the elbow flexors and muscle thickness of biceps brachii and brachialis (MT) by 8.3 ± 4.9%, 11.1 ± 7.4%, 13.5 ± 11.5%, and 10.6 ± 5.1%, respectively. In the present study, we tested the hypothesis that the muscle strength and MT would still increase when the training intensity was reduced to 2/3 or 1/3 of the peak MVC-ECC torque. Thirty-six healthy young (19-24 years) adults who had not performed resistance training were placed to three groups (n = 12/group): 2/3MVC or 1/3MVC that performed six eccentric contractions with 2/3 or 1/3 MVC-ECC load using a dumbbell 5 days a week for 4 weeks or control group that did not perform any training. Changes in the MVC-ISO, MVC-CON, MVC-ECC torque, and MT before and after the 4-week period were compared among the groups and with the group of the previous study in which six maximal eccentric contractions were performed 5 days a week for 4 weeks (MVC group; n = 12). The control and 1/3MVC groups showed no significant changes in any measures. Significant (p < 0.05) increases in MVC-ISO (10.3 ± 11.4%), MVC-CON (10.9 ± 9.5%), and MVC-ECC (9.3 ± 8.8%) torque and MT (10.1 ± 9.2%) were observed for the 2/3MVC group. These changes were not significantly different from those of the MVC group. These results suggest that the 2/3-intensity eccentric contractions with a dumbbell are as effective as maximal-intensity isokinetic eccentric contractions to induce muscle adaptations.

Optimal exercise intensity for improving executive function in patients with attention deficit hyperactivity disorder: systematic review and network meta-analysis.

This study aimed to compare and rank the effectiveness of optimal exercise intensity in improving executive function in patients with ADHD (Attention deficit hyperactivity disorder, ADHD) through a comprehensive comparison of direct and indirect evidence. A systematic search was performed in five electronic databases to explore the optimal exercise intensity for improving executive function in patients with ADHD by directly and indirectly comparing a variety of exercise intervention intensities. In addition, the isolated effects of exercise on improving executive function in patients with ADHD were explored through classical meta-analysis of paired direct comparisons. Twenty-nine studies were retrieved and included in this study. Classical paired meta-analysis showed that for the patients with ADHD in the age group of 7-17 years, statistical difference was observed for all the parameters of exercise interventions (intensity, frequency, period, and training method), the three dimensions of executive function, the use of medication or not, the high and low quality of the methodological approach. Network meta-analysis showed that high-intensity exercise training was optimal for improving working memory (97.4%) and inhibitory function (85.7%) in patients with ADHD. Meanwhile, moderate-intensity exercise training was optimal for improving cognitive flexibility (77.3%) in patients with ADHD. Moderate to high intensity exercise training shows potential for improving executive function in these patients. Therefore, we recommend applying high-intensity exercise intervention to improve executive function in patients with ADHD to achieve substantial improvement.

Effects of light- vs. heavy-load squat training on velocity, strength, power, and total mechanical work in recreationally trained men and women.

The purpose of this study was to investigate the effects of light and heavy loads in the squat exercise on kinematics and mechanical variables in recreationally trained men and women. Twenty-two men and sixteen women were assigned to 4 groups: 40% and 80% one-repetition maximum (1RM) male (M40 and M80) and female (F40 and F80). Over 6 weeks, participants performed twice a week the full back-squat (SQ) exercise with initially equated relative volume load (Sets*Repetitions/Set*%1RM). All groups performed different amounts of work (p < 0.05), while relative work (work/1RM) only differed between load groups (p < 0.001). There was no significant Time*Sex*Load interaction. Based on the magnitude of effect sizes: M80 achieved small improvements in the SQ maximum isometric force (MIF; ES = 0.43, 95% CI [0.16, 0.81]); small gains in squat estimated 1RM strength were observed in the 80%-1RM groups (M80: 0.42 [0.18, 0.77]; F80: 0.44 [0.26, 0.76]) and the F40 group (0.42 [0.17, 0.81]); all groups made moderate to large gains in the average velocity attained against heavy loads (> 60%1RM; F40: 1.20 [0.52, 2.27]; F80: 2.20 [1.23, 3.93]; M40: 0.85 [0.29, 1.59]; M80: 1.03 [0.55, 1.77]), as well as small to moderate improvements in the average velocity against light loads (< 60%1RM; F40: 0.49[-0.24, 1.68]; F80: 1.10 [0.06, 3.16]; M40: 0.80 [0.41, 1.35]; M80: 0.93 [0.25, 1.84]). Lastly, only the F40 group showed small improvements in countermovement jump (CMJ) height (ES = 0.65 [0.14, 1.37]). In conclusion, light and heavy loads produced similar strength gains in men and women when initially equated by relative volume load, although the standardized mean differences suggest nuances depending on the sample and task.

Effects of plyometric training on different 8-week training intensity distributions in well-trained endurance runners.

The aim of this four-armed parallel group randomized-controlled trial was to evaluate if plyometric training could have different effects on running performance and physiological adaptations depending on the training intensity distribution (TID) in an 8-week intervention in endurance athletes. Sixty well-trained male runners (age: 34 ± 6 years, relative ⩒O2peak : 69 ± 3 ml kg-1  min-1 ) were recruited and allocated to a pyramidal (PYR), pyramidal + plyometric training (PYR + PLY), polarized (POL), and polarized + plyometric training (POL + PLY) periodization. The periodization patterns were isolated manipulations of TID, while training load was kept constant. Participants were tested pre- and post-intervention for body mass, velocity at 2 and 4 mmol·L-1 of blood lactate concentration (vBLa2, vBLa4), absolute and relative ⩒O2peak and 5-km running time trial performance, counter movement jump and squat jump. There were significant group × time interactions for vBla4 (p = 0.0235), CMJ (p = 0.0234), SJ (p = 0.0168), and 5-km running time trial performance (p = 0.0035). Specifically, vBla4 and 5-km running time trial performance showed the largest post-intervention improvements in PYR + PLY (2.4% and 1.6%) and POL + PLY (2.1% and 1.8%), respectively. No significant interactions were observed for body mass, absolute and relative ⩒O2peak , peak heart rate, lactate peak and rating of perceived exertion. In conclusion, an 8-week training periodization seems to be effective in improving performance of well-trained endurance runners. Including plyometric training once a week appeared to be more efficacious in maximizing running performance improvements, independently from the TID adopted.

Training characteristics and performance of two male elite short-distance triathletes: From junior to "world-class".

OBJECTIVE: The sports-science literature lacks data on training and performance characteristics of international elite athletes over multiple seasons. The present case study provided general training characteristics and performance data of two male short-distance triathletes in the Junior, U23, and international Elite categories. METHODS: General training and performance data of two male elite triathletes were described in swimming, cycling, and running segments from the 2015 to 2022 season. The training load was presented using the ECO model while the training intensity distribution (TID) was a triphasic model. RESULTS: Both triathletes increased their performance throughout the seasons. Triathlete A increased his VO2max in cycling by 20.6%, in running by 16.7%. His power at VO2max and his speed at VO2max by 18.9% and 11.0%, respectively. Triathlete B improved his VO2max by 17.8% in cycling, by 16.1% in running and his power at VO2max by 24%, and his speed at VO2max by 14.3%. The triathletes trained on average 14-17 h a week. The TID model was polarized. CONCLUSIONS: To achieve the top international level, it is necessary to consider the following measures: training load progression; improvements in physiological variables; and participation in international events starting from youth categories.

The Impact of Aerobic Exercise on HDL Quantity and Quality: A Narrative Review.

High-density lipoproteins comprise roughly 25-30% of the circulating proteins involved in the transport of lipids in circulation. These particles differ in size and lipid composition. Recent evidence suggests that the quality of HDL particles (which depends on shape, size and the composition of proteins and lipids determining HDL functionality) may be more important than their quantity. The functionality of HDL is mirrored by its cholesterol efflux activity, as well as its antioxidant (including the protection of LDL against oxidation), anti-inflammatory and antithrombotic properties. The results of many studies and meta-analyses imply the beneficial impact of aerobic exercise on HDL-C levels. Physical activity was found to be usually associated with an increase in HDL cholesterol and a decrease in LDL cholesterol and triglycerides. Exercise, apart from inducing quantitative alterations in serum lipids, exerts a beneficial impact on HDL particle maturation, composition and functionality. The Physical Activity Guidelines Advisory Committee Report underlined the importance of establishing a program recommending exercises that enable attainment of maximal advantage at the lowest level of risk. The aim of this manuscript is to review the impact of different types of aerobic exercise (various intensities and durations) on the level and quality of HDL.

Effect of Polarized Training on Cardiorespiratory Fitness of Untrained Healthy Young Adults: A Randomized Control Trial with Equal Training Impulse.

To explore the effects of 8-week polarized training (POL), high-intensity interval training (HIIT), and threshold training (THR) interventions on the cardiorespiratory fitness (CRF) of untrained healthy young adults. This study recruited 36 young adults and randomly assigned them to POL, HIIT, THR, or control (CG) groups to undergo an 8-week training intervention. The training impulse applied to all three intervention groups was identical. The training intensity was divided into Zone 1, 2, and 3 (Z1, Z2 and Z3) on the basis of the ventilatory thresholds (VT). The weekly training intensity distribution for POL was 75% of Z1 and 25% of Z3; HIIT was 100% of Z3 and THR was 50% of Z1 and 50% of Z2. Each group underwent Bruce protocol testing and supramaximal testing before, during, and after the intervention; relevant CRF parameters were assessed. 8 weeks of POL and HIIT significantly increased VT2 (p < 0.05); 8 weeks of POL, HIIT, THR and significantly increased VO2max and TTE (p < 0.05). The effect size of POL in relation to VO2max and TTE improvements was greater than that of HIIT and THR (g = 2.67 vs. 1.26 and 1.49; g = 2.75 vs. 2.05 and 1.60). Aerobic training models with different intensity distributions have different time effects on improving CRF. Relative to HIIT and THR, POL improved more variables of CRF. Therefore, POL is a feasible aerobic training method for improving CRF.

Effects of 16 weeks of pyramidal and polarized training intensity distributions in well-trained endurance runners.

The aim of this study was to investigate the effects of four different training periodizations, based on two different training intensity distributions during a 16-week training block in well-trained endurance runners. Sixty well-trained male runners were divided into four groups. Each runner completed one of the following 16-week training interventions: a pyramidal periodization (PYR); a polarized periodization (POL); a pyramidal periodization followed by a polarized periodization (PYR â†’ POL); and a polarized periodization followed by a pyramidal periodization (POL â†’ PYR). The PYR and POL groups trained with a pyramidal or polarized distribution for 16 weeks. To allow for the change in periodization for the PYR â†’ POL and POL â†’ PYR groups, the 16-week intervention was split into two 8-week phases, starting with pyramidal or polarized distribution and then switching to the other. The periodization patterns were isolated manipulations of training intensity distribution, while training load was kept constant. Participants were tested pre-, mid- and post-intervention for body mass, velocity at 2 and 4 mmol·L-1 of blood lactate concentration (vBLa2, vBLa4), absolute and relative peak oxygen consumption ( V ˙ O 2 peak ) and 5-km running time trial performance. There were significant group × time interactions for relative V ˙ O 2 peak (p < 0.0001), vBLa2 (p < 0.0001) and vBLa4 (p < 0.0001) and 5-km running time trial performance (p = 0.0001). Specifically, participants in the PYR â†’ POL group showed the largest improvement in all these variables (~3.0% for relative V ˙ O 2 peak , ~1.7% for vBLa2, ~1.5% for vBLa4, ~1.5% for 5-km running time trial performance). No significant interactions were observed for body mass, absolute V ˙ O 2 peak , peak heart rate, lactate peak and rating of perceived exertion. Each intervention effectively improved endurance surrogates and performance in well-trained endurance runners. However, the change from pyramidal to polarized distribution maximized performance improvements, with relative V ˙ O 2 peak representing the only physiological correlate.

Training Session and Detraining Duration Affect Lower Limb Muscle Strength Maintenance in Middle-Aged and Older Adults: A Systematic Review and Meta-Analysis.

Muscle strength after detraining is still higher than the level before training, which is an important issue for middle-aged and older adults. The purpose of the present study was to examine the effects of detraining duration (DD), resistance training duration (RTD), and intensity on the maintenance of resistance training (RT) benefits after detraining in middle-aged and older adults. A systematic search yielded 15 randomized control trails (n = 383) eligible for inclusion. The results showed that RTD ≥ 24 weeks and DD ≥ RTD, the RT benefits were still significantly maintained even with medium and low intensity (standardized mean difference = 1.16, 95% confidence interval, CI [0.38, 1.94], p = .004). When RTD < 24 weeks and DD ≤ RTD, only the high-intensity groups maintained the RT benefits (DD, 4-6 weeks: standardized mean difference = 0.71, 95% CI [0.34, 1.08], p = .0002; DD 8-16 weeks: standardized mean difference = 1.35, 95% CI [0.66, 2.04], p = .0001). However, when DD > RTD, the RT benefits were not maintained even with high intensity. In summary, when RTD was less than 24 weeks, RTD > DD was an important factor in maintaining muscle strength.

Effects of different intensities of continuous training on vascular inflammation and oxidative stress in spontaneously hypertensive rats.

We aimed to study the effects and underlying mechanism of different intensities of continuous training (CT) on vascular inflammation and oxidative stress in spontaneously hypertensive rats (SHR). Rats were divided into five groups (n = 12): Wistar-Kyoto rats sedentary group (WKY-S), sedentary group (SHR-S), low-intensity CT group (SHR-L), medium-intensity CT group (SHR-M) and high-intensity CT group (SHR-H). Changes in body mass, heart rate and blood pressure were recorded. The rats were euthanized after 14 weeks, and blood and vascular tissue samples were collected. Haematoxylin and Eosin staining was used to observe the aortic morphology, and Western blot was used to detect the expression of mesenteric artery proteins. After CT, the mean arterial pressures improved in SHR-L and SHR-M and increased in SHR-H compared with those in SHR-S. Vascular inflammation and oxidative stress levels significantly subsided in SHR-L and SHR-M (p < 0.05), whereas in SHR-H, only vascular inflammation significantly subsided (p < 0.05), and oxidative stress remained unchanged (p > 0.05). AMPK and SIRT1/3 expressions in SHR-L and SHR-M were significantly up-regulated than those in SHR-S (p < 0.05). These results indicated that low- and medium-intensity CT can effectively reduce the inflammatory response and oxidative stress of SHR vascular tissue, and high-intensity CT can improve vascular tissue inflammation but not oxidative stress.

Long-term physical training in adolescent sprint and middle distance swimmers alters the composition of circulating T and NK cells which correlates with soluble ICAM-1 serum concentrations.

PURPOSE: It remains unknown how different training intensities and volumes chronically impact circulating lymphocytes and cellular adhesion molecules. First, we aimed to monitor changes in NK and T cells over a training season and relate these to training load. Second, we analyzed effects of training differences between swimmers on these cells. Finally, we examined if changes in lymphocytes were associated with sICAM-1 concentrations. METHODS: We analyzed weekly training volume, training intensity, proportions of T and NK cells and serum sICAM-1 in eight sprint (SS) and seven middle-distance swimmers (MID) at three points over a 16-week training period: at the start (t0), after 7 weeks of increased training load (t7) and after 16 weeks, including 5-day taper (t16). RESULTS: Training volume of all swimmers was statistically higher and training intensity lower from t0-t7 compared to t7-t16 (p = 0.001). Secondly, training intensity was statistically higher in SS from t0-t7 (p = 0.004) and t7-t16 (p = 0.015), while MID had a statistically higher training volume from t7-t16 (p = 0.04). From t0-t7, NK (p = 0.06) and CD45RA+CD45RO+CD4+ cells (p < 0.001) statistically decreased, while CD45RA-CD45RO+CD4+ cells (p = 0.024) statistically increased. In a subgroup analysis, SS showed statistically larger increases in NK cells from t7-t16 than MID (p = 0.012). Lastly, sICAM-1 concentrations were associated with changes in CD45RA-CDRO+CD4+ cells (r = - 0.656, p = 0.08). CONCLUSION: These results indicate that intensified training in swimmers resulted in transient changes in T and NK cells. Further, NK cells are sensitive to high training volumes. Lastly, sICAM-1 concentrations may be associated with the migration and maturation of CD4+ cells in athletes.

Train like an athlete: applying exercise interventions to manage type 2 diabetes.

Exercise elicits high energy demands, stimulating cardiorespiratory function and substrate mobilisation and oxidation. Repeated bouts of exercise lead to whole-body adaptations, which improve athletic performance. Distinct exercise modalities and intensities and nutritional conditions pose specific physiological challenges, subsequently inducing different adaptations to training. Athletes often modify these variables to achieve individualised training goals and maximise performance. Exercise training improves glycaemic control in individuals with type 2 diabetes; however, the precise training regimen that confers the most beneficial metabolic adaptations in this population is unknown. In this review, we discuss how modifying exercise type, intensity and modality and nutritional status affects the beneficial effects of exercise on glycaemic control in individuals with type 2 diabetes. Evidence indicates that greater improvements in glycaemic control can be achieved through combined aerobic and resistance training regimens compared with either training type alone. However, the increased frequency of training and a greater number of exercise bouts during combined programmes could be responsible for apparent advantages over a single training modality. The beneficial effects of aerobic exercise on glycaemic control seem to rise with training intensity, with superior adaptations achieved by high-intensity interval training (HIT). In addition, training with low carbohydrate availability ('training low') improves cardiorespiratory function and skeletal muscle oxidative capacity more than conventional training in healthy untrained individuals. Examinations of various training regimens are warranted to assess the safety, efficacy, feasibility and beneficial effects in the type 2 diabetes population. Just like competitive athletes, individuals with type 2 diabetes should be encouraged to adopt training regimens that improve fitness and metabolism. Graphical abstract.

Birth sex ratio in the offspring of professional male soccer players: influence of exercise training load.

STUDY QUESTION: Can the exercise training load of elite male athletes influence the sex ratio of their offspring? SUMMARY ANSWER: This is the first study assessing the influence of exercise training load on the offspring sex ratio of children from male professional athletes, observing a bias toward more females being born as a result of both high-intensity and high-volume loads, with intensity having the greatest effect. WHAT IS KNOWN ALREADY: There is a relatively constant population sex ratio of males to females among various species; however, certain events and circumstances may alter this population sex ratio favoring one sex over the other. STUDY DESIGN, SIZE, DURATION: Observational, descriptive cross-sectional study with a duration of 3 months. PARTICIPANTS/MATERIALS, SETTING, METHODS: Seventy-five male professional soccer players from First Division soccer teams. Offspring variables were sex of the offspring, number of children and order of birth. Exercise training variables were volume and intensity. MAIN RESULTS AND THE ROLE OF CHANCE: Total offspring was 122 children (52 males (42.6%), 70 females (57.4%)). Analysis revealed that increase in either the volume (P < 0.001) or intensity (P < 0.001) of training by the players shifted the birth offspring ratio more toward females. Within the sample of females born, more births (i.e. number) were observed as a consequence of training at the highest intensity (45 out of 70; P < 0.001), no such pattern occurred within males (P > 0.05). When female versus male births were compared within each intensity, only the high-intensity comparison was significant (45 (75%) females vs 15 (25%) males, P < 0.001). LIMITATIONS, REASONS FOR CAUTION: While this is the first study assessing differences in the sex ratio of the offspring of male athletes (i.e. soccer players), we acknowledge there are limitations and confounders within our approach; e.g. small sample size, ethnic background and variations in the timing of intercourse relative to ovulation as well as in sex hormone levels. As such, we propose that future research is needed to confirm or refute our findings. It is recommended that such work expand on the measurements obtained and conduct direct assessment of sperm characteristics. WIDER IMPLICATIONS OF THE FINDINGS: The findings of the study support the fact that different stressors on the body may alter the sex of the offspring. While in the present study the stressor is the excessive training load of soccer players, other events may lead to similar results. The bias in offspring sex ratio may have important implications for demography and population dynamics, as well as genetic trait inheritance. STUDY FUNDING/COMPETING INTEREST(S): There is no funding nor competing interests. TRIAL REGISTRATION NUMBER: N/A.

Progressions of core stabilization exercises based on postural control challenge assessment.

PURPOSE: The intensity progression of core stabilization exercises (CSEs) is usually based on personal criteria rather than on objective parameters. To develop exercise progressions for four of the most common CSEs based on the postural control challenge imposed on the participants, and to analyze the effect of participants' sex and postural control level on these progressions. METHODS: Seventy-six males and females performed five variations of front bridge, back bridge, side bridge and bird-dog exercises on two force platforms. The mean velocity of the center of pressure displacement was calculated to assess exercise intensity through the measurement of the participants' body sway (PBS). RESULTS: In general, long bridges produced higher PBS than short bridges, bridging with single leg support produced higher PBS than bridging with double leg support and bridging on a hemisphere ball produced higher PBS than bridging on the floor. The most difficult bridging variations were those performed on a hemisphere ball with single leg support. Regarding the bird-dog, two-point positions produced higher PBS than three-point positions and the positions performed on a hemisphere ball produced higher PBS than those performed on the floor. CONCLUSION: The CSE progressions obtained by males and females were very similar. However, the participants with high trunk control showed less significant differences between exercise variations than the participants with low trunk control, which shows the need to individualize the progressions according to the participants' training level. Overall, this study provides useful information to guide the prescription of CSE progressions in young physically active individuals.

A group study on the effects of a short multi-domain cognitive training in healthy elderly Italian people.

BACKGROUND: Alongside physiological cognitive ageing, nowadays there is an alarming increase in the incidence of dementia that requires communities to invest in its prevention. The engagement in cognitively stimulating activities and strong social networks has been identified among those protective factors promoting successful cognitive ageing. One aspect regarding cognitive stimulation concerns the relevance of the frequency of an external intervention. For this reason, the aim of this study was to evaluate the efficacy of a 3-month cognitive training program, once per week, in a group of healthy elderly aged over 60 years old. Their results were compared with those of a passive control group. METHODS: The training consisted of a weekly session of multi-domain and ecological cognitive exercises performed in small homogenous (i.e. same cognitive level) groups. The scores obtained in a neuropsychological assessment by the experimental and control groups were compared at pre- and post-training. In addition, by means of a questionnaire, we also evaluated the indirect effect of the program on participants' mood, socialization and perceived impact on everyday activities. RESULTS: Overall, the experimental group showed a general improvement in cognitive functioning following the training program, even with the frequency of once per week. Greater improvements were observed mainly on executive functions and short-term memory, but general cognitive functioning and non-verbal reasoning also showed a tendency to an improvement. It is noteworthy that a majority of the participants reported to have subjectively experienced an improvement in their everyday life and a positive influence on both mood and socialization. CONCLUSIONS: These results show that even a low-intensity training program is able to promote some of the protective factors that support successful cognitive ageing. Moreover, this multi-domain approach proved to be an excellent training method to transfer gains not only to other cognitive domains, but also to everyday living. TRIAL REGISTRATION: NCT03771131 ; the study was retrospectively registered on December 7th 2018.

Development, Dynamic Modeling, and Multi-Modal Control of a Therapeutic Exoskeleton for Upper Limb Rehabilitation Training.

Robot-assisted training is a promising technology in clinical rehabilitation providing effective treatment to the patients with motor disability. In this paper, a multi-modal control strategy for a therapeutic upper limb exoskeleton is proposed to assist the disabled persons perform patient-passive training and patient-cooperative training. A comprehensive overview of the exoskeleton with seven actuated degrees of freedom is introduced. The dynamic modeling and parameters identification strategies of the human-robot interaction system are analyzed. Moreover, an adaptive sliding mode controller with disturbance observer (ASMCDO) is developed to ensure the position control accuracy in patient-passive training. A cascade-proportional-integral-derivative (CPID)-based impedance controller with graphical game-like interface is designed to improve interaction compliance and motivate the active participation of patients in patient-cooperative training. Three typical experiments are conducted to verify the feasibility of the proposed control strategy, including the trajectory tracking experiments, the trajectory tracking experiments with impedance adjustment, and the intention-based training experiments. The experimental results suggest that the tracking error of ASMCDO controller is smaller than that of terminal sliding mode controller. By optimally changing the impedance parameters of CPID-based impedance controller, the training intensity can be adjusted to meet the requirement of different patients.

Increasing upper limb training intensity in chronic stroke using embodied virtual reality: a pilot study.

BACKGROUND: Technology-mediated neurorehabilitation is suggested to enhance training intensity and therefore functional gains. Here, we used a novel virtual reality (VR) system for task-specific upper extremity training after stroke. The system offers interactive exercises integrating motor priming techniques and embodied visuomotor feedback. In this pilot study, we examined (i) rehabilitation dose and training intensity, (ii) functional improvements, and (iii) safety and tolerance when exposed to intensive VR rehabilitation. METHODS: Ten outpatient stroke survivors with chronic (>6 months) upper extremity paresis participated in a ten-session VR-based upper limb rehabilitation program (2 sessions/week). RESULTS: All participants completed all sessions of the treatment. In total, they received a median of 403 min of upper limb therapy, with 290 min of effective training. Within that time, participants performed a median of 4713 goal-directed movements. Importantly, training intensity increased progressively across sessions from 13.2 to 17.3 movements per minute. Clinical measures show that despite being in the chronic phase, where recovery potential is thought to be limited, participants showed a median improvement rate of 5.3% in motor function (Fugl-Meyer Assessment for Upper Extremity; FMA-UE) post intervention compared to baseline, and of 15.4% at one-month follow-up. For three of them, this improvement was clinically significant. A significant improvement in shoulder active range of motion (AROM) was also observed at follow-up. Participants reported very low levels of pain, stress and fatigue following each session of training, indicating that the intensive VR intervention was well tolerated. No severe adverse events were reported. All participants expressed their interest in continuing the intervention at the hospital or even at home, suggesting high levels of adherence and motivation for the provided intervention. CONCLUSIONS: This pilot study showed how a dedicated VR system could deliver high rehabilitation doses and, importantly, intensive training in chronic stroke survivors. FMA-UE and AROM results suggest that task-specific VR training may be beneficial for further functional recovery both in the chronic stage of stroke. Longitudinal studies with higher doses and sample sizes are required to confirm the therapy effectiveness. TRIAL REGISTRATION: This trial was retrospectively registered at ClinicalTrials.gov database (registration number NCT03094650 ) on 14 March 2017.

The within-participant correlation between perception of effort and heart rate-based estimations of training load in elite soccer players.

The measurement of relative physiological stress during training is important because this is the stimulus for the long-term adaptive response. Measurements of perceived exertion (RPE) have been reported to correlate with the heart rate during field-based training sessions. Nevertheless, there are few studies on how well RPE tracks with the heart rate over repeated training sessions in elite soccer players. Therefore, we aimed to quantify the within-participant correlations between variability in session-RPE (sRPE) and the heart rate in elite male soccer players, and to determine whether the playing position moderated these correlations. The field-based training of four central defenders, four wide defenders, six central midfielders, two wide midfielders and three attackers from an elite English Premier League squad were monitored over an entire in-season competitive period, giving a total of 1010 individual training sessions for study. Correlations between session-RPE and heart rates were quantified using a within-participant model. The correlation between changes in sRPE and heart rates was r = 0.75 (95% CI: 0.71-0.78). This correlation remained high across the various player positions (wide-defender, r = 0.81; central-defender, r = 0.74; wide midfielder, r = 0.70; central midfielder, r = 0.70; attacker, r = 0.84; P < 0.001). The correlation between changes in RPE and heart rates, measured during a season-long period of field-based training, is high in a sample of elite soccer players.

The IGF-1/cortisol ratio as a useful marker for monitoring training in young boxers.

Training effects on plasma insulin-like growth factor-1 (IGF-1)/cortisol ratio were investigated in boxers. Thirty subjects were assigned to either the training or the control group (n = 15 in both). They were tested before the beginning of training (T0), after 5 weeks of intensive training (T1), and after 1 week of tapering (T2). Physical performances (Yo-Yo intermittent recovery test level-1), training loads, and blood sampling were obtained at T0, T1, and T2. Controls were only tested for biochemical and anthropometric parameters at T0 and T2. A significantly higher physical performance was observed at T2 compared to T1. At T1, cortisol levels were significantly increased whereas IGF-1 and insulin-like growth factor binding protein-3 (IGFBP-3) levels remained unchanged compared to baseline. At T2, cortisol levels decreased while IGF-1 and IGFBP-3 levels increased. The IGF-1/cortisol ratio decreased significantly at T1 and increased at T2, and its variations were significantly correlated with changes in training loads and Yo-Yo intermittent recovery test level 1 (IRT1) performance over the training period. Cortisol variations correlated with changes in training load (r = 0.64; p < 0.01) and Yo-Yo IRT1 performance (r = 0.78; p < 0.001) at T1 whereas IGF-1 variations correlated only with changes in Yo-Yo IRT1 performance at T2 (r = 0.71; p < 0.001). It is concluded that IGF-1/cortisol ratio could be a useful tool for monitoring training loads in young trained boxers.

Relative activity of respiratory muscles during prescribed inspiratory muscle training in healthy people.

[Purpose] This study aimed to determine the effects of different intensities of inspiratory muscle training on the relative respiratory muscle activity in healthy adults. [Subjects and Methods] Thirteen healthy male volunteers were instructed to perform inspiratory muscle training (0%, 40%, 60%, and 80% maximal inspiratory pressure) on the basis of their individual intensities. The inspiratory muscle training was performed in random order of intensities. Surface electromyography data were collected from the right-side diaphragm, external intercostal, and sternocleidomastoid, and pulmonary functions (forced expiratory volume in 1 s, forced vital capacity, and their ratio; peak expiratory flow; and maximal inspiratory pressure) were measured. [Results] Comparison of the relative activity of the diaphragm showed significant differences between the 60% and 80% maximal inspiratory pressure intensities and baseline during inspiratory muscle training. Furthermore, significant differences were found in sternocleidomastoid relative activity between the 60% and 80% maximal inspiratory pressure intensities and baseline during inspiratory muscle training. [Conclusion] During inspiratory muscle training in the clinic, the patients were assisted (verbally or through feedback) by therapists to avoid overactivation of their accessory muscles (sternocleidomastoid). This study recommends that inspiratory muscle training be performed at an accurate and appropriate intensity through the practice of proper deep breathing.