Repetition Maximum Research Articles

Impact of Complete Intermittent Blood Flow Restriction in Upper Limbs Strength and Neural Function

ABSTRACT Purpose: We aimed to investigate the chronic effects of low-load strength training (LT) with complete intermittent blood flow restriction (IBFR) on neural adaptations and strength in biceps brachii. Methods: Nineteen volunteers were randomly assigned into two different 9-week training protocols consisting of three assessment weeks and six training weeks: (a) LT with complete IBFR (LT-IBFR; n = 10) and (b) LT without complete IBFR (LT; n = 9). Strength was evaluated by predicted 1 repetition maximum (1RM) at weeks 1, 5, and 9 and neural function by root mean square (RMS) and median frequency (MDF) at sessions 1, 7, and 12 during the first three and last three repetitions. Both groups performed three sets of Scott curl with 20% of predicted 1RM interspersed with 90s rest twice a week. Results: No changes were found in predicted 1RM throughout the training protocols nor between groups. LT-IBFR group showed lower RMS in the first set than LT for the first three repetitions and higher RMS in all sets for the last three repetitions with decreases in this value across the sets with no longitudinal changes for both groups. MDF in the first three repetitions did not differentiate between groups, however, in the last three repetitions, MDF were lower for LTIBFR group in all sets and it increased across the sets for this condition with no chronical changes for both groups in both repetitions zones. These results suggest that LT-IBFR may be ineffective for increasing Q5 strength and it did not promote chronic neural adaptations.

Non-Local Muscle Fatigue Impairs Mean Propulsive Velocity During Strength Loading in Strength-Trained Men

ABSTRACT Purpose: This study examined the acute influence of a bench press (BP) loading on the explosive squat (SQ) performance and vice versa. Methods: Nineteen strength-trained men completed 2 experimental sessions consisting of either a SQ+BP loading or a BP+SQ loading with 3 × 5 + 3 × 3 repetitions at 80% of the 1-repetition maximum in a randomized order. SQ and BP mean propulsive velocity (MPV) were assessed during both loadings, at baseline (T0) as well as immediately after the first (T1) and second strength loading (T2). Results: Both BP and SQ MPV decreased between T0 and T1 in SQ+BP (−6.13 ± 6.13%, p = .014, g = 0.485 and −9.11 ± 7.23%, p < .001, g = 0.905, respectively) and BP+SQ (−15.15 ± 7.69%, p < .001, g = 1.316 and −7.18 ± 6.16%, p < .001, g = 0.724, respectively). Mean BP MPV was lower in set 2 to set 6 in SQ+BP when compared to BP+SQ (−7.90% − 9.88%, all p < .05, g = 0.523–0.808). Mean SQ MPV was lower in set 1 and set 4 in BP+SQ when compared to SQ+BP (−4.94% − 5.22%, all p < .001, g = 0.329–0.362). Conclusions: These results demonstrate that the presence of non-local muscle fatigue affects the movement velocity. Therefore, if a training program aims to perform strength training exercises with maximal movement velocity, it is essential to carefully evaluate whether upper and lower body exercises should be carried out within close proximity.

Vertical Jump and Relative Strength are Strongly Associated with Change of Direction in Professional Male Basketball Players

Purpose: The aim of this study was to examine the predictors of change of direction (COD) in highly trained/national level male basketball players using field assessments.&#x0D; Methods: Eight professional male basketball players (age: 24.0 ± 5.5 years; body mass index (BMI): 24.1 ± 1.6 kg m-2) volunteered for participation in this study. All the evaluations were carried out during 2 sessions as follows: First day_1) body composition, 2) unilateral and bilateral squat jump (SJ) and countermovement (CMJ), and 3) Yo-Yo intermittent recovery test level 1 (Yo-Yo IR1); Second day_1) COD performance, and 2) one repetition maximum (1RM) hang clean (HC) and bench press (BP). A linear regression was performed to evaluate the determinants of COD amongst all other measured variables. Furthermore, we applied Pearson correlation coefficient and in the case of non-normally distributed variables, Spearman’s correlation coefficient for the selected variables.&#x0D; Results: The linear regression indicated that only SJ height was a significant determinant of COD (R2 = 58.8%, p = 0.016). Significant correlations were identified between COD test and SJ (r = -0.75, p = 0.034; very large), and relative HC 1 RM (r = -0.74, p = 0.038; very large).&#x0D; Conclusions: The associations found between COD performance and physical parameters should be considered when developing athletic conditioning programs. Especially, the vertical jump heigh could explain the greatest variability in COD performance..

The Effect of Joint Hypermobility Syndrome on DOMS and Recovery Time.

Previous research has reported that people with Joint Hypermobility Syndrome (JHS) and Ehlers-Danlos Syndrome (EDS) generally experience a high rate of muscular injury and pain. However, there is limited research comparing the recovery times and length of Delayed Onset Muscle Soreness (DOMS) in individuals with JHS to non-hypermobile individuals in response to exercise. The purpose of this study was to investigate JHS and its effects on DOMS and its recovery time. Quasi-experimental, observational comparison. Two groups including a hypermobile group (score >4 on Beighton Scale) and a non-hypermobile group all took part in five-second long standing eccentric bicep curls based using their one- repetition maximum (1-RM) of their dominant arm to failure in order to induce DOMS. Visual analog pain scale (VAS), McGill pain scale, resting arm angle, girth, and the pressure pain threshold, all domains of DOMS, were measured over a five-day period. Results were analyzed using ANOVA with time as the repeated factor. Both groups experienced DOMS following the eccentric exercise. However, VAS reporting was significantly greater in the hypermobile group compared to the non-hypermobile group and there was a significant difference over time. However, other variables did not reveal any other significant findings between groups. Individuals with JHS may experience greater DOMS and require more time to recover between treatment sessions. Therapists need to be aware that patients with hypermobility may experience higher pain levels related to exercise, and they need to adjust treatment parameters appropriately. 2b.

Comparison of kinematics and electromyography in the last repetition during different maximum repetition sets in the barbell back squat.

The barbell squat is an exercise used to strengthen the lower limbs, with implications for both performance in sports and improving movement during everyday tasks. Although the exercise is being trained across a variety of repetition ranges, the technical requirements may vary, affecting appropriate repetition range for specific training goals. A randomised within-subject design was used to compare kinematics and surface electromyography (EMG) in the lower extremities during different concentric phases (pre-, sticking- and post-sticking region) of the last repetition when performing squats at different repetition maximums (RMs). Thirteen strength-trained men (age: 23.6 ± 1.9 years; height: 181.1 ± 6.5 cm; body mass: 82.2 kg, 1RM: 122.8 ± 16.2, relative strength: 1.5 ± 0.2 x body mass in external load) performed a 1, 3, 6, and 10RM squat, in a randomised order. The main findings were that barbell-, ankle-, knee- and hip kinematics were similar across different repetition ranges, except for a smaller trunk lean at 1RM in the pre-sticking region compared to other repetitions and in the sticking region compared to 10RM (p ≤ 0.04). Furthermore, 1RM revealed significantly higher EMG amplitude in the vastus lateralis, gastrocnemius and soleus in the sticking and post-sticking regions when compared to 10RM. It was concluded that 10RM may locally fatigue the vastus lateralis and plantar flexors, explaining the lower EMG amplitude. The observed differences indicate that requirements vary for completing the final repetition of the 10RM compared to the 1RM, an important aspect to consider in training to enhance 1RM strength.

Novel Blood Flow Restriction Therapy Protocol for the Treatment of Postamputation Weakness and Pain due to Osteosarcoma: A Case Study

BACKGROUND: Pain and weakness are 2 commonly reported postamputation symptoms. The purpose of this case report is to propose a novel blood flow restriction (BFR) protocol to address pain and weakness in a patient with transtibial limb loss. CASE PRESENTATION: A 36-year-old male 2 months after transtibial amputation presented for evaluation and treatment of his postamputation pain, weakness, and poor functional mobility. The patient completed a novel BFR strength protocol twice per week for 12 weeks. OUTCOME AND FOLLOW-UP: Amputee Mobility Predictor, L Test Measure of Functional Mobility, 2-minute walk test, 30-second sit to stand, hamstring force, single-limb leg press repetition maximum, hip abduction endurance test, and numeric pain scale preintervention and postintervention were measured. The patient achieved the minimal detectable change for the L-Test and 2MWT, resulting in meaningful improvement in the patient’s strength and function following the blood flow restriction protocol. DISCUSSION: This case supports the use of blood flow restriction to address postamputation weakness and pain in a physical therapy setting. JOSPT Cases 2024;4(1):1-7. Epub 30 November 2023. doi:10.2519/josptcases.2023.11327

Resistance Training With Different Velocity Loss Thresholds Induce Similar Changes in Strength and Hypertrophy.

Andersen, V, Paulsen, G, Stien, N, Baarholm, M, Seynnes, O, and Saeterbakken, AH. Resistance training with different velocity loss thresholds induce similar changes in strengh and hypertrophy. J Strength Cond Res 38(3): e135-e142, 2024-The aim of this study was to compare the effects of 2 velocity-based resistance training programs when performing resistance training with matched training volume. Ten resistance-trained adults volunteered (age, 23 ± 4.3 years; body mass, 68 ± 8.9 kg; and height, 171 ± 8 cm) with a mean resistance training experience of 4.5 years. A within person, between leg design was used. For each subject, the legs were randomly assigned to either low velocity loss (LVL) threshold at 15% or high velocity loss (HVL) threshold at 30% velocity loss. Leg press and leg extension were trained unilaterally twice per week over a period of 9 weeks. Before and after the intervention, both legs were tested in 1 repetition maximum (RM) (kg), maximal voluntary contraction (MVC) (N), rate of force development (N·s -1 ), average velocity (m·s -1 ), and power output (W) at 30, 45, 60, and 75% of 1 RM (all in unilateral leg press). Furthermore, muscle thickness (mm) of the vastus lateralis and rectus femoris, pennation angle (°) of the vastus lateralis, and the fascicle length (mm) of the vastus lateralis were measured using ultrasound imaging. The data were analyzed using mixed-design analysis of variance. No differences between the legs in any of the variables were found; however, both low and HVL were effective for increasing 1 RM (ES = 1.25-1.82), MVC (effect size [ES] = 0.42-0.64), power output (ES = 0.31-0.86), and muscle thickness (ES = 0.24-0.51). In conclusion, performing velocity-based resistance training with low and HVL with equal training volume resulted in similar effects in maximal and explosive strength in addition to muscular adaptations.

Accuracy and reliability of perception of bar velocity loss for autoregulation in resistance exercise

Background The perception of bar velocity loss (PVL) can be used as an alternative method for autoregulating intraset repetitions during velocity-based training. This study analyzed the accuracy and reliability of the PVL as a method to autoregulate the intraset repetitions using a moderate velocity loss (VL) threshold (15–30%). Methods A total of 22 resistance-trained men were familiarized with the PVL in a single session. Test–retest was performed in two sessions 1 week apart, in which participants completed three sets of bench press and back squat at 40, 60, and 80% 1 repetition maximum (1RM). Participants stopped the sets when they reached a moderate VL zone using their PVL. Accuracy was assessed by analyzing whether the mean VL (actual) and the lower and upper limits of the confidence interval (CI) (95%) of each set were within the established VL range and quantifying the relative frequency of correctly interrupted sets. Test–retest reliability was examined by the intraclass correlation coefficient and coefficient of variation. Results PVL showed acceptable accuracy in both exercises at 60 and 80% 1RM (50–65% success rate) and retest for all loads (53–76% success rate). Similar PVL percentages were observed between most of the sets for the test and retest ( p &gt; 0.05). Accuracy improved during the retest, especially for bench press (40% 1RM) and back squat (40 and 80% 1RM). PVL was not reliable in the test–retest comparison. Conclusion PVL can be a strategy with acceptable accuracy to autoregulate the intraset repetitions in a moderate zone (VL15–30%), but its reliability does not appear satisfactory after one familiarization session.

Cluster Method: Effects on Performance in Handball

The aim of this study was to examine the effects of six week traditional and cluster training method applied in female handball players on speed, strength and throwing power. 32 handball players participated in this study. 16 athletes were assigned in the Cluster Training Group (CTG), 16 athletes in the Traditional Training Group (TTG). The training continued for six weeks, three days a week, during the preparation period of the annual training program. Both groups practiced leg extension/flexion, pulldown, butterfly, bench press, deep squat. The CTG performed 80% of repetition maximum (1RM), 4 repetitions with a 20-second rest, total of 12 repetitions and 2 sets. The TTG, on the other hand, performed 80% of 1RM, 12 repetitions, 2-3-minute rest between sets, and again 2 sets. At the beginning and end of the training, 10 and 20 m speed, hand grip strength, standing long jump, vertical jump, throwing speed, squat and bench press performance measurements were recorded. A statistically significant difference was found in the performance values within the group (p&amp;lt;0.05). A statistically significant difference was found between groups in the vertical jump and standing long jump (p&amp;lt;0.05). There was no statistically significant difference between groups in terms of the other performances (p&amp;gt;0.05). As a result, it was seen that the cluster method was effective on the development of the jump force. Considering the difference between cluster and traditional training methods, we can say that the cluster method provides more advantages than the traditional method in branches that require explosive strength.

A single dose multi-ingredient pre-workout supplement enhances upper body resistance exercise performance.

Multi-ingredient pre-workout supplements (MIPS) are commonly used by individuals looking to enhance exercise performance and augment adaptations to training. However, the efficacy of commercially available MIPS is largely dependent on the ingredient profile, and new formulations should be investigated to determine their effectiveness. Therefore, the purpose of this study was to examine the effects of a commercially available MIPS product on performance during an upper body resistance exercise protocol. Twenty resistance-trained participants (10 men, 10 women) volunteered to complete this double-blind, placebo-controlled, crossover study consisting of 3 visits. Visit 1 consisted of body composition, 1-repetition maximum (1RM) testing, and familiarization. Visits 2 and 3 consisted of supplementation with either MIPS or placebo (PLA) 1 h prior to completion of an upper body resistance exercise workout during which power output, repetitions completed, rating of perceived exertion (RPE), and perceived recovery were recorded. Assessments of reaction time, isometric mid-thigh pull, and perceived levels of focus, energy, fatigue, and "muscle pump" were also completed before supplementation, 1 h after supplementation, and immediately after exercise. Statistical analysis revealed significant main effects of trial for reaction time (p < 0.001) and bench press peak power (p = 0.026) indicating better performance during the MIPS trial. Furthermore, total number of repetitions completed significantly increased (p = 0.003) during the MIPS (96.90 ± 21.31 repetitions) trial compared to PLA (89.50 ± 18.37 repetitions). Additionally, overall session RPE was significantly lower (p = 0.002) during the MIPS (7.6 ± 1.2) trial compared to PLA (8.3 ± 0.9). These findings suggest that acute supplementation with this MIPS improved upper body resistance exercise performance while reducing participant RPE. Further research should investigate the efficacy of chronic supplementation with this MIPS as the acute response provided an ergogenic benefit.

A Novel Case Study Approach to the Investigation of Leg Strength Asymmetry and Rugby League Player's Multidirectional Speed.

Helme, M, Emmonds, S, Low, C, and Till, K. A novel case study approach to the investigation of leg strength asymmetry and Rugby League player's multidirectional speed. J Strength Cond Res 38(5): 941-947, 2024-Leg strength and multidirectional speed qualities have repeatedly been linked with increased performance during Rugby League (RL) match play and associated with career attainment. However, very little of this evidence for strength has been gained through unilateral measurements with no study available that has examined the impact of strength asymmetry, in this population, on speed qualities in RL players. Therefore, this study examined the association between unilateral strength, and as a novel development, the subject with the most extreme asymmetry was identified for further analysis. Fifty RL players undertook the rear foot elevated split squat 5 repetition maximum, 20-m linear sprint, and modified 505 change of direction test. The mean leg strength for the group was 88.92 ± 12.59 kg; when divided by body mass, the mean relative strength (REL) was 1.03 ± 0.17 kg·kg -1 , and the mean asymmetry was 3.21 ± 5.70%. The subject with the greatest asymmetry (subject A) had an imbalance of 33% and a mean leg strength of 75 kg (REL = 0.78 kg·kg -1 ) and a body mass 1 SD above the group mean. Analysis of the group's data and that of subject A did not indicate that leg strength asymmetry was either frequent or harmful, with respect to speed performance. However, relative leg strength was associated with both improved linear and multidirectional speed. Practitioners are recommended to prioritize the development of relative leg strength and disregard the aspiration for between leg performance symmetry.

Combined Accentuated Eccentric Loading and Rest Redistribution in High-Volume Back Squat: Acute Stimulus and Fatigue.

Chae, S, Long, SA, Lis, RP, McDowell, KW, Wagle, JP, Carroll, KM, Mizuguchi, S, and Stone, MH. Combined accentuated eccentric loading and rest redistribution in high-volume back squat: Acute stimulus and fatigue. J Strength Cond Res 38(4): 648-655, 2024-The purpose of this study was to examine acute stimulus and fatigue responses to combined accentuated eccentric loading and rest redistribution (AEL + RR). Resistance-trained men ( n = 12, 25.6 ± 4.4 years, 1.77 ± 0.06 m, and 81.7 ± 11.4 kg) completed a back squat (BS) 1 repetition maximum (1RM) and weight releaser familiarization session. Three BS exercise conditions (sets × repetitions × eccentric-concentric loading) consisted of (a) 3 × (5 × 2) × 110/60% (AEL + RR 5), (b) 3 × (2 × 5) × 110/60% (AEL + RR 2), and (c) 3 × 10 × 60/60% 1RM (traditional sets [TS]). Weight releasers (50% 1RM) were attached to every first repetition of each cluster set (every first, third, fifth, seventh, and ninth repetition in AEL + RR 5 and every first and sixth repetition in AEL + RR 2). The AEL + RR 5 resulted in greater total volume load (sets × repetitions × eccentric + concentric loading) (6,630 ± 1,210 kg) when compared with AEL + RR 2 (5,944 ± 1,085 kg) and TS (5,487 ± 1,002 kg). In addition, AEL + RR 5 led to significantly ( p < 0.05) greater rating of perceived exertion (RPE) after set 2 and set 3 and lower blood lactate (BL) after set 3 and 5, 15, and 25 minutes postexercise than AEL + RR 2 and TS. There was a main effect of condition for BL between AEL + RR 5 (5.11 ± 2.90 mmol·L -1 ), AEL + RR 2 (6.23 ± 3.22 mmol·L -1 ), and TS (6.15 ± 3.17 mmol·L -1 ). In summary, AEL + RR 5 results in unique stimulus and fatigue responses. Although it may increase perceived exertion, coaches could use AEL + RR 5 to achieve greater back squat total volume load while reducing BL accumulation.

Lower Repetition Induces Similar Postactivation Performance Enhancement to Repetition Maximum After a Single Set of Heavy-Resistance Exercise.

Chen, C-F, Chuang, C-Y, Wang, C-C, Liu, S-A, Chang, H-W, and Chan, K-H. Lower repetition induces similar postactivation performance enhancement to repetition maximum after a single set of heavy-resistance exercise. J Strength Cond Res 38(5): 848-855, 2024-The study was divided into 2 parts to investigate the acute postactivation performance enhancement (PAPE) responses to lower repetitions at the same load of 87% 1 repetition maximum (1RM) in the upper and lower body. In part 1, 14 athletes performed plyometric push-up (PPU) after the conditioning activity (CA) of bench press (BP). In part 2, 13 athletes performed a countermovement jump (CMJ) after the CA of parallel squat (PS). Subjects completed 3, 4, or 5 repetitions (trials CA-3, CA-4, or CA-5) of BP or PS in randomized and counterbalanced order. The velocity of each movement of the trial was recorded. The PPU or CMJ was tested every 2 minutes after the trial up to 12 minutes to assess the Post-Max and optimal individual PAPE time. The mean velocity of the last movement of BP in CA-5 was significantly lower than that in CA-3 (0.23 ± 0.06 vs. 0.28 ± 0.06 m·second -1 , p < 0.05), and the velocity of PS in CA-4 or CA-5 was significantly lower than that in CA-3 (0.53 ± 0.07 and 0.50 ± 0.05 vs. 0.57 ± 0.07 m·second -1 , p < 0.05). The peak force of PPU and jump height of CMJ at Post-Max in the 3 trials were significantly greater than those at Pre ( p < 0.05). There were no significant differences among trials in the optimal individual PAPE times in either part of the study. A single set of 87% 1RM resistance exercises with 3 or 4 repetitions in both the upper body and the lower body induces similar PAPE to repetition maximum.

Muscular stress is equal when resistance exercise with blood flow restriction is matched in total work volume: A cross-sectional, cross-over study.

We compared muscular metabolic stress during exercise performed at multiple intensities, from very low to moderate, with blood flow restriction (BFR) adjusted by the same work volume. Twenty-five healthy young adults performed unilateral plantar flexion at 1 repetition/2 s in a magnetic resonance system. The BFR exercise protocols were as follows: (A) exercise with 10% of one repetition maximum (1-RM) for 360 s, (B) 15% 1-RM for 240 s, (C) 20% 1-RM for 180 s, (D) 30% 1-RM for 120 s, and (E) 40% 1-RM for 90 s. All protocols had the same total work volume (load × repetitions = 1800). A high-intensity protocol at 65% 1-RM without BFR (60 s) was also performed for comparison. We used 31 P-magnetic resonance spectroscopy to evaluate the muscular metabolic stress in the subjects' calf muscle, defined as decreases in phosphocreatine and intramuscular pH. The phosphocreatine depletion (A: 15.6 ± 0.7, B: 14.8 ± 0.8, C: 15.2 ± 0.6, D: 14.3 ± 0.6, E: 10.9 ± 0.5 mM; no significant difference [ns]) and the intramuscular pH decrease (A: 6.82 ± 0.02, B: 6.84 ± 0.01, C: 6.83 ± 0.02, D: 6.83 ± 0.02, E: 6.77 ± 0.02; ns) at the end of each exercise were similar and greater than those produced by the 65% 1-RM without BFR. If the total work volumes are equal, the metabolic stress in exercising muscle may reach similar levels at the end of exercise with BFR and could provide similar successful training effects.

The magnitude of correlation between deadlift 1RM and jumping performance is sports dependent.

Based on the assumption of maximal strength as a basic ability, several studies show a high influence of maximum strength on jumping performance in several sport athletes. However, there is a wide range of correlations from r = 0.17-0.9 between squat 1RM and jumping performance in different sports. Additionally, there are only a few studies investigating the influence of deadlift one repetition maximum (1RM) on jumping performance. Thus, this study aimed to investigate the correlations between 1RM in the deadlift on jumping performance using the countermovement jump height (CMJ) and squat jump height (SJ) considering different sports. 103 athletes with experience in the deadlift from soccer, basketball, American football, powerlifting as well as participants from different sports without any deadlift experience (control group) were included to this study. Overall statistics showed a significant moderate influence of deadlift 1RM (r = 0.301-0.472) on jumping performance. However, subgroup analysis showed no significant correlation between deadlift 1RM and jumping performance in control participants, while moderate correlations could be detected in powerlifters (r = 0.34-0.39), soccer players (r = 0.437-0.46), American football players (0.584-0.62) and high correlations in basketball players (r = 0.809-0.848) showing significant influence of type of sport on correlations between deadlift maximum strength and jumping performance. Presented results underline movement velocity- and task specificity of strength training routines which is discussed in the light of the respective sports.

Relative Cross-Education Training Effects of Male Youth Exceed Male Adults.

Ben Othman, A, Anvar, SH, Aragão-Santos, JC, Behm, DG, and Chaouachi, A. Relative cross-education training effects of male youth exceed male adults. J Strength Cond Res 38(5): 881-890, 2024-Cross-education has been studied extensively with adults, examining the training effects on contralateral homologous muscles. There is less information on the cross-education effects on contralateral heterologous muscles and scant information comparing these responses between adults and youth. The objective was to compare cross-education training effects in male youth and adults to contralateral homologous and heterologous muscles. Forty-two male children (10-13-years) and 42 adults (18-21-years) were tested before and following an 8-week unilateral, dominant or nondominant arm, chest press (CP) training program or control group (14 subjects each). Unilateral testing assessed dominant and nondominant limb strength with leg press and CP 1 repetition maximum (1RM), knee extensors, elbow extensors (EE), elbow flexors, and handgrip maximum voluntary isometric contraction (MVIC) strength and shot put distance and countermovement jump height. Upper-body tests demonstrated large magnitude increases, with children overall exceeding adults ( p = 0.05- p < 0.0001, η2 : 0.51, 10.4 ± 11.1%). The dominant trained limb showed significantly higher training adaptations than the nondominant limb for the adults with CP 1RM ( p = 0.03, η2 : 0.26, 6.7 ± 11.5%) and EE ( p = 0.008, η2 : 0.27, 8.8 ± 10.3%) MVIC force. Unilateral CP training induced significantly greater training adaptations with the ipsilateral vs. contralateral limb ( p = 0.008, η2 : 0.93, 27.8 ± 12.7%). In conclusion, children demonstrated greater training adaptations than adults, upper-body strength increased with no significant lower-body improvements, and ipsilateral training effects were greater than contralateral training in adults.

Effects of aging and lifelong aerobic exercise on expression of innate immune components in skeletal muscle of women.

This study examined the effects of aging and lifelong aerobic exercise on innate immune system components in the skeletal muscle of healthy women in the basal state and after an unaccustomed resistance exercise (RE) challenge. We also made exploratory between-sex comparisons with our previous report on men. Three groups of women were studied: young exercisers (YE, n = 10, 25 ± 1 yr, V̇o2max: 44 ± 2 mL/kg/min), lifelong aerobic exercisers with a 48 ± 2 yr training history (LLE, n = 7, 72 ± 2 yr, V̇o2max: 26 ± 2 mL/kg/min), and old healthy nonexercisers (OH, n = 10, 75 ± 1 yr, V̇o2max: 18 ± 1 mL/kg/min). Ten Toll-like receptors (TLRs)1-10, TLR adaptors (Myd88, TRIF), and NF-κB pathway components (IκBα, IKKβ) were assessed at the mRNA level in vastus lateralis biopsies before and 4 h after RE [3×10 repetitions, 70% 1-repetition maximum (1RM)]. Basal TLR1-10 expression was minimally influenced by age or LLE in women (TLR9 only; OH > YE, +43%, P < 0.05; OH > LLE, +30%, P < 0.10) and was on average 24% higher in women versus men. Similarly, basal adaptor expression was not influenced (P > 0.05) by age or LLE in women but was on average 26% higher (myeloid differentiation primary response 88, Myd88) and 23% lower [Toll interleukin (IL)-1 receptor-containing adaptor-inducing interferon-γ, TRIF] in women versus men. RE-induced changes in women, independent of the group, in TLR3, TLR4, TLR6 (∼2.1-fold, P < 0.05), Myd88 (∼1.2-fold, P < 0.10), and IκBα (∼0.3-fold, P < 0.05). Although there were some similar RE responses in men (TLR4: 2.1-fold, Myd88: 1.2-fold, IκBα: 0.4-fold), several components responded only in men to RE (TLR1, TLR8, TRIF, and IKKβ). Our findings support the sexual dimorphism of immunity, with women having greater basal skeletal muscle TLR expression and differential response to unaccustomed exercise than men.NEW & NOTEWORTHY We recently reported that aging increases basal expression of many Toll-like receptors (TLRs) in men and lifelong aerobic exercise does not prevent this effect. In addition, a resistance exercise (RE) challenge increased the expression of many TLRs. Here we show that basal TLR expression is minimally influenced by aging in women and findings support the sexual dimorphism of immunity, with women having greater basal skeletal muscle TLR expression and a differential response to unaccustomed exercise than men.

Peak patellar tendon force progressions during heavy load single-leg squats on level ground and decline board

BackgroundProgressive tendon loading programs for patellar tendinopathy typically include single-leg squats with heavy weights either on level ground or on a decline board. Changes in patellar tendon force due to variations of the heavy load single-leg squat have not yet been objectively quantified. The objective of this study was to investigate the influence of the mass of an external weight and the use of a decline board on the peak patellar tendon force during a heavy load single-leg squat. MethodsTwelve healthy participants performed single-leg back squats on a decline board and level ground at 70%, 80% and 90% of their one repetition maximum. Three-dimensional kinematics and ground reaction forces were measured and the peak patellar tendon force was calculated using musculoskeletal modelling. A two-way repeated measures ANOVA determined the main effects for the mass of the external weights and the use of a decline board as well as their interaction effect. FindingsPeak patellar tendon forces were significantly higher on the decline board compared to level ground (p < 0.05). Neither on the decline board, nor on level ground did the peak patellar tendon force increase significantly when increasing the external weights (p > 0.05). InterpretationProgression in peak patellar tendon forces during a heavy load single-leg squat can only be obtained with a decline board. Increasing the mass of the external weight from 70% to 90% of the one repetition maximum does not result in a progressively higher peak patellar tendon force.

Acute effect of stretching performed before a resistance exercise session using different intervals on maximum repetitions performance in recreationally trained adults

The present study proposed to compare the acute effect of stretching (SE) before resistance exercise (RE) sessions using different intervals (30 vs. 60 vs. 120 seconds) on maximal repetition performance of recreationally trained adults. Twenty men (age: 29.5 ± 7.05 years; height: 82.92 ± 8.47 kg; weight: 1.78 ± 0.07 cm; body mass index: 26.03 ± 1.55 m2kg-1) recreationally trained in RE (≥ 6 months) completed 4 interventions: 1) RE with 60-second intervals (RE60"), 2) SE plus RE with 30-second intervals (SE+RE30"), 3) SE plus RE with 60-second intervals (SE+RE60"), and 4) SE plus RE with 120-second intervals (SE+RE120"). The RE consisted of three sets until muscle failure of the following exercises: bench press, bench press 35°, decline bench press, biceps curl, and biceps curl 45° at 80% of 10RM. The SE involved two sets of 30-second static SE for chest and biceps separated by a 40-second passive interval. The maximum number of repetitions performed until muscle failure was counted at the end of each set. The results of this study show a progressive reduction in maximum repetitions performance between sets and exercises in tested protocols with and without SE. Significant reductions were presented for the SE+RE30" protocol compared to the RE60" and SE+RE120" protocols. The present study suggests that 60" intervals between sets are necessary to avoid a significant reduction in maximum repetitions performance. Keywords: Neuromuscular performance, strength, strength training

Higher resistance training volume offsets muscle hypertrophy nonresponsiveness in older individuals.

The magnitude of muscle hypertrophy in response to resistance training (RT) is highly variable between individuals (response heterogeneity). Manipulations in RT variables may modulate RT-related response heterogeneity; yet, this remains to be determined. Using a within-subject unilateral design, we aimed to investigate the effects of RT volume manipulation on whole muscle hypertrophy [quadriceps muscle cross-sectional area (qCSA)] among nonresponders and responders to a low RT dose (single-set). We also investigated the effects of RT volume manipulation on muscle strength in these responsiveness groups. Eighty-five older individuals [41M/44F, age = 68 ± 4 yr; body mass index (BMI) = 26.4 ± 3.7 kg/m2] had one leg randomly allocated to a single (1)-set and the contralateral leg allocated to four sets of unilateral knee-extension RT at 8-15 repetition maximum (RM) for 10-wk 2 days/wk. Pre- and postintervention, participants underwent magnetic resonance imaging (MRI) and unilateral knee-extension 1-RM strength testing. MRI typical error (2× TE = 3.27%) was used to classify individuals according to responsiveness patterns. n = 51 were classified as nonresponders (≤2× TE) and n = 34 as responders (>2× TE) based on pre- to postintervention change qCSA following the single-set RT protocol. Nonresponders to single-set training showed a dose response, with significant time × set interactions for qCSA and 1-RM strength, indicating greater gains in response to the higher volume prescription (time × set: P < 0.05 for both outcomes). Responders improved qCSA (time: P < 0.001), with a tendency toward higher benefit from the four sets RT protocol (time × set: P = 0.08); on the other hand, 1-RM increased similarly irrespectively of RT volume prescription (time × set: P > 0.05). Our findings support the use of higher RT volume to mitigate nonresponsiveness among older adults.NEW & NOTEWORTHY Using a within-subject unilateral design, we demonstrated that increasing resistance training (RT) volume may be a simple, effective strategy to improve muscle hypertrophy and strength gains among older adults who do not respond to low-volume RT. In addition, it could most likely be used to further improve hypertrophic outcomes in responders.