Effects of resistance training on heat shock response (HSR), HSP70 expression, oxidative stress, inflammation, and metabolism in middle-aged people

Resistance training (RT) can increase the heat shock response (HSR) in the elderly. As middle-aged subjects already suffer physiological declines related to aging, it is hypothesized that RT may increase the HSR in these people. To assess the effects of resistance training on heat shock response, intra and extracellular HSP70, oxidative stress, inflammation, body composition, and metabolism in middle-aged subjects. Sixteen volunteers (40 – 59 years) were allocated to two groups: the trained group (n = 7), which performed 12 weeks of RT; and the physically inactive—control group (n = 9), which did not perform any type of exercise. The RT program consisted of 9 whole-body exercises (using standard gym equipment) and functional exercises, carried out 3 times/week. Before and after the intervention, body composition, muscle mass, strength, functional capacity, and blood sample measurements (lipid profile, glucose, insulin, oxidative damage, TNF-α, the HSR, HSP70 expression in leukocytes, and HSP72 in plasma) were performed. The HSR analysis demonstrated that this response is maintained at normal levels in middle-aged people and that RT did not cause any improvement. Also, RT increases muscle mass, strength, and functional capacity. Despite no additional changes of RT on the antioxidant defenses (catalase, glutathione peroxidase, and reductase) or inflammation, lipid peroxidation was diminished by RT (group x time interaction, p = 0.009), indicating that other antioxidant defenses may be improved after RT. HSR is preserved in middle-aged subjects without metabolic complications. In addition, RT reduces lipid peroxidation and can retard muscle mass and strength loss related to the aging process. (AU)

Effects of resistance training on heat shock response (HSR), HSP70 expression, oxidative stress, inflammation, and metabolism in middle-aged people

Resistance training (RT) can increase the heat shock response (HSR) in the elderly. As middle-aged subjects already suffer physiological declines related to aging, it is hypothesized that RT may increase the HSR in these people. To assess the effects of resistance training on heat shock response, intra and extracellular HSP70, oxidative stress, inflammation, body composition, and metabolism in middle-aged subjects. Sixteen volunteers (40 – 59 years) were allocated to two groups: the trained group (n = 7), which performed 12 weeks of RT; and the physically inactive—control group (n = 9), which did not perform any type of exercise. The RT program consisted of 9 whole-body exercises (using standard gym equipment) and functional exercises, carried out 3 times/week. Before and after the intervention, body composition, muscle mass, strength, functional capacity, and blood sample measurements (lipid profile, glucose, insulin, oxidative damage, TNF-α, the HSR, HSP70 expression in leukocytes, and HSP72 in plasma) were performed. The HSR analysis demonstrated that this response is maintained at normal levels in middle-aged people and that RT did not cause any improvement. Also, RT increases muscle mass, strength, and functional capacity. Despite no additional changes of RT on the antioxidant defenses (catalase, glutathione peroxidase, and reductase) or inflammation, lipid peroxidation was diminished by RT (group x time interaction, p = 0.009), indicating that other antioxidant defenses may be improved after RT. HSR is preserved in middle-aged subjects without metabolic complications. In addition, RT reduces lipid peroxidation and can retard muscle mass and strength loss related to the aging process. (AU)

Effects of resistance training on heat shock response (HSR), HSP70 expression, oxidative stress, inflammation, and metabolism in middle-aged people.

Resistance training (RT) can increase the heat shock response (HSR) in the elderly. As middle-aged subjects already suffer physiological declines related to aging, it is hypothesized that RT may increase the HSR in these people. To assess the effects of resistance training on heat shock response, intra and extracellular HSP70, oxidative stress, inflammation, body composition, and metabolism in middle-aged subjects. Sixteen volunteers (40 - 59 years) were allocated to two groups: the trained group (n = 7), which performed 12 weeks of RT; and the physically inactive-control group (n = 9), which did not perform any type of exercise. The RT program consisted of 9 whole-body exercises (using standard gym equipment) and functional exercises, carried out 3 times/week. Before and after the intervention, body composition, muscle mass, strength, functional capacity, and blood sample measurements (lipid profile, glucose, insulin, oxidative damage, TNF-α, the HSR, HSP70 expression in leukocytes, and HSP72 in plasma) were performed. The HSR analysis demonstrated that this response is maintained at normal levels in middle-aged people and that RT did not cause any improvement. Also, RT increases muscle mass, strength, and functional capacity. Despite no additional changes of RT on the antioxidant defenses (catalase, glutathione peroxidase, and reductase) or inflammation, lipid peroxidation was diminished by RT (group x time interaction, p = 0.009), indicating that other antioxidant defenses may be improved after RT. HSR is preserved in middle-aged subjects without metabolic complications. In addition, RT reduces lipid peroxidation and can retard muscle mass and strength loss related to the aging process.

Hamstring-to-quadriceps activation ratio during lower-limb strengthening exercises.

Multiple exercises included in strength training involve greater activation of the quadriceps compared to hamstring muscles, which may lead to knee joint imbalances. The aim of this study was to examine the ratio of surface electromyography (sEMG) activity hamstring and quadriceps muscle groups (hamstring-to-quadriceps activation ratio; H:Q EMG), as well as lateral to medial hamstring activation ratio (LH:MH) in parallel squat, Romanian deadlift, hip thrust, lying leg curl and seated knee extension. The H:Q EMG was greater during lying leg curl compared to other exercises during both the concentric and eccentric phase, however the Romanian deadlift and hip thrust also resulted in relatively high H:Q EMG. Pairwise comparisons revealed that LH:MH was greater in the parallel squat compared to the Romanian deadlift and hip thrust in the concentric phase, and compared to the Romanian deadlift and hip thrust during the eccentric phase. Our data suggests that the lying leg curl promotes the greatest hamstring activation and H:Q EMG, amongst the exercises investigated, while also providing relatively homogenous LH:MH. The lying leg curl should be considered as a primary exercise in rehabilitation and training programmes, aiming to proportionally activate LH:MH and increase H:Q EMG, which may improve knee muscle balance.

Total and regional body composition are related with aerobic fitness performance in elite futsal players.

Body composition (i.e., fat and lean mass profile) has been related to aerobic performance, an essential capacity for futsal athletes. The present study aimed to verify the relationship between total and regional body composition (percentage of fat and lean mass) with aerobic performance in elite futsal players. Male professional futsal athletes (n = 44) from two Brazilian National Futsal League teams and athletes representing the National team participated in this study. Body composition was evaluated using DXA (Dual-Energy X-ray Absorptiometry) and aerobic fitness by ergospirometry. There was a negative (p < 0.05) correlation between maximum oxygen uptake and maximal velocity reached with total body (r = -0.53; r = -0.58), trunk (r = -0.52; r = -0.56) and lower-limb (r = -0.46; r = -0.55) fat mass percentage. Lower-limb lean mass percentage had a positive (p < 0.05) correlation with maximum oxygen uptake (r = 0.46) and maximal velocity (r = 0.55). In conclusion, total and regional body composition present a relationship with aerobic performance in professional futsal players.

Low Pre-Season Hamstring-to-Quadriceps Strength Ratio Identified in Players Who Further Sustained In-Season Hamstring Strain Injuries: A Retrospective Study from a Brazilian Serie A Team.

A common pre-season injury prevention assessment conducted by professional football clubs is the hamstring-to-quadriceps (H:Q) strength ratio calculated by peak torque (PT). However, it is debatable whether players that present low pre-season H:Q ratios are more susceptible to further sustaining in-season hamstring strain injuries (HSI). Based upon retrospective data from a Brazilian Serie A football squad, a particular season came to our attention as ten out of seventeen (~59%) professional male football players sustained HSI. Therefore, we examined the pre-season H:Q ratios of these players. H:Q conventional (CR) and functional (FR) ratios, and the respective knee extensor/flexor PT from the limbs of players further sustaining in-season HSI (injured players, IP) were compared to the proportional number of dominant/non-dominant limbs from uninjured players (UP) in the squad. FR and CR were ~18-22% lower (p < 0.01), whereas quadriceps concentric PT was ~25% greater for IP than UP (p = 0.002). Low scores of FR and CR were correlated (p < 0.01) with high levels of quadriceps concentric PT (r = -0.66 to -0.77). In conclusion, players who sustained in-season HSI had lower pre-season FR and CR compared to UP, which appears to be associated with higher levels of quadriceps concentric torque than hamstring concentric or eccentric torque.

Similar body composition, muscle size, and strength adaptations to resistance training in lacto-ovo-vegetarians and non-vegetarians.

There is a popular belief that meat consumption is necessary to optimize adaptations to strength training (ST), but evidence to support this hypothesis is scarce. Therefore, this study aimed to compare ST adaptations in lacto-ovo-vegetarians (LOV) and non-vegetarians (NV) with adjusted protein intake per meal. Sixty-four LOV and NV performed 12 weeks of ST and were instructed to ingest at least 20 g of protein in each main meal during the experimental period. Quadriceps femoris muscle thickness (QFMT), knee extension one-repetition maximum (1RM), and isometric peak torque (PT), as well as participants' body composition were assessed before and after the intervention. Dietary intake was assessed throughout the study. After 12 weeks, similar increases in QFMT (LOV: 9.2 ± 5.4; NV: 5.5 ± 8.1 mm), knee extension 1RM (LOV: 24.7 ± 11.1; NV: 21.6 ± 9.8 kg), and PT (LOV: 29.8 ± 33.4; NV: 17.5 ± 19.4 N m) and lean body mass (LOV: 1.3 ± 0.9; NV: 1.4 ± 1.4 kg), alongside a decrease in body fat mass (LOV: -0.5 ± 1.6; NV -0.8 ± 1.6 kg) were observed in both groups at the end of the training period (p < 0.05). LOV had lower protein consumption than NV throughout the study (p < 0.05), but participants reached intake of at least 1.2 g of protein/kg/day during the experimental period. In conclusion, LOV and NV displayed similar improvements in muscle mass, strength, and in body composition after 12 weeks of ST, suggesting that meat consumption and higher protein intake in NV did not bring about further benefits to early adaptations to ST. This study was registered in Clinical Trials (NCT03785002) on 24 December 2018.

Impact of Resistance Training Volume on Physical and Perceptual Outcomes of Breast Cancer Survivors Submitted to a Combined Training Program: A Randomized, Single-Blinded Study.

BACKGROUND: To determine the effect of resistance training volume on physical and perceptual outcomes of breast cancer survivors submitted to a combined training program. DESIGN: Randomized single-blinded study. METHODS: Nineteen breast cancer survivor women were randomized to a single-set (SS) or a multiple-set (MS) group. Both groups completed an 8-week combined training intervention in which the SS and MS groups performed 1 and 3 sets per resistance exercise, respectively. The following outcomes were assessed preintervention and postintervention: maximal knee extension dynamic strength (1-repetition maximum), quadriceps muscle thickness, peak oxygen uptake, time to exhaustion, cancer-related fatigue, and quality of life. RESULTS: Both interventions increased knee extension 1-repetition maximum (SS: 29.8% [37.5%]; MS: 19.3% [11.8%]), quadriceps muscle thickness (9.4% [4.1%]; 8.9% [5.9%]), and quality of life (4.3% [6.3%]; 7.9% [9.0%]), with no difference between the groups. However, only MS improved cancer-related fatigue (-2.1% [1.7%]) and time to exhaustion (21.3% [14.9%]), whereas peak oxygen uptake remained unchanged in both groups. CONCLUSIONS: Cancer-related fatigue and time to exhaustion, improved only in the MS group after the intervention. On the other hand, similar knee extension 1-repetition maximum, quadriceps muscle thickness, and quality of life improvements were observed in breast cancer survivors irrespective of the resistance training volume performed.

Exercise volume load in women with breast cancer: Study protocol for the ABRACE randomized clinical trial.

Background: An increased number of breast cancer patients are challenged by acute and persistent treatment side effects. Oncology guidelines have been establishing physical exercise to counteract several treatment-related toxicities throughout cancer care. However, evidence regarding the optimal dose-response, feasibility, and the minimal resistance exercise volume and/or intensity remains unclear. The ABRACE Study will assess the impact of different resistance training volumes (i.e., single or multiple sets) combined with aerobic exercise on physical and psychological outcomes of breast cancer patients undergoing primary treatment. Methods: This study is a randomized, controlled, three-armed parallel trial. A total of 84 participants, aged ≥18 years, with breast cancer stages I-III, initiating adjuvant or neoadjuvant chemotherapy (≤50% of sessions completed) will be randomized to multiple sets resistance training plus aerobic training group, single set resistance training plus aerobic training group or control group. Neuromuscular and cancer-related fatigue (primary outcomes), muscle strength, muscle thickness, muscle quality by echo intensity, body composition, cardiorespiratory capacity, functional performance, upper-body endurance and quality of life will be measured before and after the 12-week intervention. Our analysis will follow the intention-to-treat approach and per-protocol criteria, with additional sub-group analysis. Discussion: Findings support prescribing exercise during chemotherapy for breast cancer and elucidate the potential role of different resistance training volumes as a management strategy for physical and psychological impairments in women with early-stage breast cancer. Our main hypothesis is for superiority in physical and psychological outcomes for both training groups compared to the control group, with no difference between single or multiple sets groups. Trial registration: Clinical trials NCT03314168.

Relationship Between Dual-Energy X-Ray Absorptiometry, Ultrasonography, and Anthropometry Methods to Estimate Muscle Mass and Muscle Quality in Older Adults.

Decreased muscle quality (MQ) may explain functional capacity impairments during aging. Thus, it is essential to verify the interaction between MQ and functional capacity in older adults. We investigated the relationship between MQ and functional capacity in older adults (n = 34; 66.3 ± 4.6 year). MQ was estimated by maximum strength of knee extensors normalized to thigh muscle mass. Maximum strength was assessed on an isokinetic dynamometer (peak torque), while dual-energy X-ray absorptiometry (DXA), ultrasonography, and anthropometry were used to determine thigh muscle mass. Functional capacity was verified by 30-s sit to stand and timed up and go tests. Significant correlations were found between MQ assessed by DXA with 30-s sit to stand (r = .35; p < .05) and timed up and go (r = -.47; p < .05), and MQ assessed by anthropometry with timed up and go (r = -.41; p < .05), but not between MQ assessed by ultrasonography with functional capacity (p > .05). No significant relationship between muscle mass with functional capacity was observed. Thus, MQ assessed by DXA and MQ assessed by anthropometry may partially explain functional capacity in older adults. Interestingly, muscle mass alone did not explain performance in functional tests in this population.

Cardiometabolic effects of early v. delayed time-restricted eating plus energetic restriction in adults with overweight and obesity: an exploratory randomised clinical trial.

This exploratory study investigated the effects of early v. delayed time-restricted eating (TRE) plus caloric restriction (CR) on body weight, body composition and cardiometabolic parameters in adults with overweight and obesity. Adults (20-40 years) were randomised to one of three groups for 8 weeks: early time-restricted eating (eTRE; 08.00-16.00) plus CR, delayed time-restricted eating (dTRE; 12.00-20.00) plus CR or only CR (CR; 08.00-20.00). All groups were prescribed a 25 % energy deficit relative to daily energy requirements. Thirteen participants completed the study in the eTRE and CR groups and eleven in the dTRE group (n 37). After the interventions, there was no significant difference between the three groups for any of the outcomes. Compared with baseline, significant decreases were observed in the body weight (eTRE group: -4·2 kg; 95 % CI, -5·6, -2·7; dTRE group: -4·8 kg; 95 % CI, -5·9, -3·7; CR: -4·0 kg; 95 % CI, -5·9, -2·1), fat mass (eTRE group: -2·9 kg; 95 % CI, -3·9, -1·9; dTRE group: -3·6 kg; 95 % CI, -4·6, -2·5; CR: -3·1 kg; 95 % CI, -4·3, -1·8) and fasting glucose levels (eTRE group: -4 mg/dl; 95 % CI, -8, -1; dTRE group: -2 mg/dl; 95 % CI, -8, 3; CR: -3 mg/dl; 95 % CI, -8, 2). In a free-living setting, TRE with a energetic deficit, regardless of the time of day, promotes similar benefits in weight loss, body composition and cardiometabolic parameters. However, given the exploratory nature of our study, further investigation is needed to confirm these findings.

Acute Blood Pressure Response to High- and Moderate-Speed Resistance Exercise in Older Adults With Hypertension.

An increase in blood pressure (BP) occurs during resistance exercise; attention to this response may be necessary in older individuals with hypertension. We compared the BP responses following high- (HSRE) and moderate-speed resistance exercise (MSRE) (4 × 8 repetitions at 60% one-repetition maximum) and control protocol in 15 older adults with hypertension. HSRE and MSRE increased systolic BP (SBP) by the end of each set compared with preexercise and control protocol. Immediately after the fourth set, a higher SBP was observed in MSRE than HSRE (147 ± 14 vs. 141 ± 12 mmHg; p = .01). Taking an exploratory analysis of the individual response, we observed that MSRE resulted in greater mean changes and number of SBP exposures to values ≥150 mmHg (22-fold) than HSRE (10-fold). Diastolic BP increased (p < .05) with exercise, but only MSRE increased compared with the control condition (p < .05). HSRE may be an alternative for individuals in which SBP peak should be avoided.

Maximum number of repetitions at different percentages of maximum strength in older men: a crossover study

Abstract Introduction: Based on the inverse relationship between the amount of weight lifted and the maximum number of repetitions (RM) performed, the intensity prescription method based on a percentage of maximum strength (%1RM) has been widely used in different populations, including older adults. However, considerable inter-individual variability in RM performed at a given %1RM has been reported in previous studies on this topic. Aim: To compare the number of repetitions performed at 60, 75, and 90%1RM in lower and upper limb resistance exercises in older adults. Methods: Fifteen men aged between 60 and 75 years performed two preliminary sessions (familiarization + and 1RM tests) and three experimental sessions (RM tests at 60, 75, and 90%1RM on knee extension and elbow flexion exercises). Movement velocity for each concentric and eccentric muscle action was 1.5-2 s. Statistical comparisons regarding the RM performed in each %1RM were tested using the Generalized Estimating Equations analysis. Results: The RM during knee extension exercise was significantly lower when compared to elbow flexion at 60% 1RM. On the other hand, the RM during knee extension exercise was significantly higher when compared to elbow flexion at 90%1RM. A similar number of repetitions at 75%1RM were performed in both exercises. Conclusion: Physically active older men can perform different RM at 60% and 90%1RM in knee extension and elbow flexion exercises, suggesting that the use of a specific RM range cannot be associated to the same percentage of 1RM in this individuals.

Lateral and functional asymmetries in the lower limbs of college-level female handball players

Abstract Aim: The present study aimed to screen for differences in isokinetic peak torque, hamstrings-to-quadriceps ratio, and proprioception within the lower limbs of female handball athletes. Methods: Twelve college-level female handball athletes with no previous experience with resistance training performed five maximal isokinetic contractions of the knee extensors and knee flexors to determine isokinetic peak torque and hamstring-to-quadriceps ratios. Proprioception was determined by assessing passive position sense on an isokinetic dynamometer. Results: The athletes presented significantly greater (p < 0.01) knee extensors isometric peak torque for the jumping limb (144.9 ± 23.1) when compared to the non-jumping limb (132.9 ± 21.5). The Hamstrings-to-quadriceps ratio was below 0.6 for both limbs, being significantly greater (p < 0.01) for the non-jumping limb (0.56 ± 0.08) when compared to the jumping limb (0.50 ± 0.08). Conclusion: Female handball athletes that do not engage in resistance training can experience functional bilateral asymmetries in the knee extensors and knee-joint instability, as assessed by the hamstrings-to-quadriceps ratio due to the asymmetric characteristics of handball. Regular strength training might correct such asymmetries and instabilities.

Rating of Perceived Exertion as a Method to Determine Training Loads in Strength Training in Elderly Women: A Randomized Controlled Study.

Objective: The aim of this study was to compare the effects of training using loads from a repetition maximum value (%1RM) and rating of perceived exertion (RPE) in elderly women. Methods: Twenty-five elderly women (60-75 years old) were randomly assigned to a group that trained using loads determined by 1RM test (G%; n = 12) or to a group that trained using loads determined by RPE (GPE; n = 13). Elderly women trained for 12 weeks using five exercises performed with 2-3 sets of 8-15 repetitions. Loads progressed from 45% to 75% of 1RM (G%) and from 13 to 18 from Rating Perceived Exertion of Borg Scale (GPE). The outcome measures, 1RM and maximum repetitions (RMs with 70% 1RM), were assessed before, between and after training programs. Results: Increased 1RM value and RMs were observed in both groups (20-42%, p < 0.001 and 56-76%, p < 0.001, respectively, for %G; and 17-56%, p < 0.001 and 47-106%, p < 0.001, respectively, for GPE), without differences between them. Conclusions: Prescribing loads using the RPE and 1RM might be similarly effective for training elderly women in order to promote strength gains. As a practical application, RPE could be an additional method to determine training loads. In spite of the promising results of the present study, it is not possible to state that the use of RPE is effective in monitoring loads during sub maximal strength training in elderly and more research must be carried out to confirm it.

Effects of high-intensity interval training combined with traditional strength or power training on functionality and physical fitness in healthy older men: A randomized controlled trial.

Concurrent training (CT) is an efficient strategy to improve neuromuscular function and cardiorespiratory fitness in older adults, which are factors of pivotal importance for the maintenance of functional capacity with aging. However, there is a lack of evidence about the effectiveness of power training (PT) as an alternative to traditional strength training (TST) during CT. Thus, the aim of the present study was to examine the effect of 16 weeks (twice weekly) TST combined with high intensity interval training (TST + HIIT) vs. PT combined with HIIT (PT + HIIT) on functional performance, cardiorespiratory fitness and body composition in older men. Thirty five older men (65.8 ± 3.9 years) were randomly allocated into two training groups: TST + HIIT (n = 18), and PT + HIIT (n = 17). TST + HIIT performed resistance training at intensities ranging from 65% to 80% 1RM at slow controlled speed (≅ 2 s for each concentric phase), whereas PT + HIIT trained at intensities ranging from 40% to 60% of 1RM at maximal intentional speed. Both groups performed HIIT at intensities ranging from 75 to 90% of VO2peak. Participants performed functional tests (sit-to-stand, timed-up-and-go, stair climbing); cardiopulmonary exercise testing (maximal cycling power output: Wmax, peak oxygen uptake: VO2peak, cycling economy), as well as body composition assessment (DXA) before, post 8 and post 16 weeks of training. The groups improved similarly (P < 0.05) with training in all functional capacity outcomes, Wmax, cycling economy, VO2peak and body composition (P < 0.05). These findings suggest that HIIT based CT programs involving TST vs. PT are equally effective in improving functionality, cardiorespiratory fitness and body composition in healthy older men.

Brazilian Jiu-Jitsu fighters present greatest rapid and maximal strength imbalances at extreme elbow angles.

BACKGROUND: The performance of Brazilian jiu-jitsu (BJJ) fighters is dependent on rapid and maximal elbow strength actions. Appropriate strength balance between elbow flexors (F) and extensors (E) across the full joint range of motion may be required to decrease risk of injuries. AIM: To compare rapid and maximal elbow F/E strength balance through full range of motion in BJJ fighters. MATERIALS AND METHODS: Twenty-three male BJJ fighters (27.9 ± 4.6 years, 82.9 ± 10.9 kg, 174.5 ± 6.8 cm, and 15.3 ± 6.8% body fat) with 8.2 ± 6.5 years of practice volunteered to participate. Participants were tested for rate of torque development (RTD) and peak torque (PT) of elbow F and E at six angles (45°, 60°, 75°, 90°, 105°, and 120°; 0° = full extension). Rapid (F RTD/E RTD) and maximal (F PT/E PT) angle-specific torque (AST) ratios were calculated. RESULTS: Rapid AST ratio at 45° (0.66 ± 0.18) and maximal AST ratio at 45° (0.91 ± 0.16) and 120° (0.88 ± 0.20) were significantly less than all other AST ratios at mid-point angles of elbow range of motion (p < 0.05). Individual data demonstrates that both beginners and advanced BJJ fighters present overall similar rapid and maximal F/E AST imbalances. CONCLUSION: BJJ fighters present greater rapid and maximal strength imbalances at extreme-compared to mid-point angles of range of motion. Results may benefit coaches to develop strength exercises focusing on these specific angles to potentially reduce the risk of elbow injury and improve performance of BJJ fighters.

Post-match recovery of eccentric knee flexor strength in male professional football players.

OBJECTIVES: This study aimed at verifying the effect of a football match on the eccentric knee flexor strength of male professional players along a 72-h period. STUDY DESIGN: Quasi-experimental study. SETTING: Football club facilities. PARTICIPANTS: Fifteen players were assessed in four timepoints: 24 h before, immediately after, 48 h and 72 h after the match. MAIN OUTCOME MEASURES: The eccentric knee flexor strength was assessed during the Nordic hamstring exercise execution. RESULTS: Players presented a significant strength reduction immediately after match (Δ = 12%; p = 0.001; large effect size, d = 1.10), and did not recover their strength capacity within a 48 h-period (Δ = 6%; p = 0.011; moderate effect size, d = 0.57). At 72 h after the match, strength was similar to baseline levels (Δ = 3.5%; p = 0.122; small effect size, d = 0.34). Secondarily, individual response analysis considered a player 'fully recovered' when his strength deficit compared to the baseline measure was lower than the measurement coefficient of variation (i.e., <5%). Only 6 (40%) and 9 (60%) players were 'fully recovered' at 48 h and 72 h after the match, respectively. CONCLUSION: Professional football players experienced an immediately post-match drop on the eccentric knee flexor strength, and significant strength deficits persisted for a 48-h period. Some players were not recovered at 72 h after the match.

Moving forward with the echo intensity mean analysis: Exploring echo intensity bands in different age groups.

This study compared ultrasound characteristics in youth, younger adults, and older adults using two different methods of analysis: based on clusters of pixel concentration of the grayscale (i.e. EI bands) and the traditionally calculated echo intensity mean. Forty-four healthy youth (13.3 ± 1.4 y), 22 younger adults (31.8 ± 10.1 y) and 53 older adults (66.7 ± 4.6 y) volunteered for the assessment of rectus femoris EI via ultrasonography. Pixel concentration (i.e. EI bands) was calculated in intervals of 0-50, 51-100, 101-150, 151-200, and 201-255 of the gray scale, while EI mean was determined as the average pixels from 0 to 255. EI0-50 significantly decreased with group age, while EI51-100, 101-150, 151-200, 201-255 and EI mean increased (P < 0.001). The differences between groups were greater using EI0-50 compared to the EI mean (i.e. EI0-50: youth = ~353% and younger adults = ~251% > older adults; whereas EI mean: youth = ~46% and younger adults = 29% < older adults). These results potentially indicate that EI bands method offer different information than the EI mean method. In addition, EI bands may be a promising approach to understand tissue-specific adaptations to physical training and neuromuscular diseases, yet future studies should validate this method.