Repetition Maximum Research Articles

THE EFFECTS OF MODERATE TO HIGH-LOAD RESISTANCE TRAINING WITH BLOOD FLOW RESTRICTION IN HEALTHY ADULTS: A SYSTEMATIC REVIEW

INTRODUCTION AND AIMS Low-load resistance training (RT) with blood flow restriction (BFR; 20–40% of 1-repetition maximum [1RM]) increases muscle mass and strength comparably to unrestricted high-load RT. As healthy populations are not limited to low-loads, some researchers have also examined whether the adaptations to high-load RT could be enhanced with BFR, though results are inconsistent. Therefore, we conducted a systematic review to investigate whether moderate to high-load resistance training (M-HL RT) with BFR increases muscle mass or strength more than the equivalent training without BFR. METHODS Studies involving M-HL RT (≥60% 1RM) with BFR applied during exercise sets or rest intervals were included. The following databases were searched: PubMed, Web of Science, Scopus, ScienceDirect, ProQuest Central, and Google Scholar. Two researchers independently screened the titles and abstracts for eligibility based on the inclusion and exclusion criteria. The full texts of included studies were then independently screened by two researchers. Conflicts were resolved by a third researcher. Following screening, study and participant characteristics, intervention protocol for each group and outcome measures were extracted for each included study. RESULT Ten studies met the criteria for inclusion in this review. All included studies measured muscle strength, with only three reporting greater strength increases after M-HL RT with BFR compared to equivalent training without BFR. Five studies assessed muscle mass, with four reporting similar increases after M-HL RT with and without BFR. One observed a smaller increase in mass after M-HL RT with BFR than without. CONCLUSION Most studies did not observe additional benefit of applying BFR during M-HL RT for muscle strength or mass. Studies which did report benefits of BFR may be limited by methodological issues, impacting the applicability of their findings. Overall, this review does not support using BFR during M-HL RT for additional improvements in muscle strength or mass.

L-Citrulline Supplementation Improves Leg Endothelial Function and Blood Flow Responses to Plantarflexion Exercise in Hypertensive Postmenopausal Women

Menopause and hypertension are associated with macro- and microvascular endothelial dysfunction at rest. Arginine deficiency and low nitric oxide (NO) synthesis may contribute to reduced muscle blood flow (BF) and oxygen delivery to exercising muscles. Improving BF to calf muscles may enhance physical activity. L-Citrulline supplementation (CIT) has improved resting macrovascular endothelial function via increased arginine availability for NO synthesis. Thus, the purpose of this study was to examine the effects of CIT on resting microvascular endothelial function and BF responses to plantarflexion exercise (PFE) in hypertensive postmenopausal women. We hypothesized that CIT would improve microvascular function and BF responses to PFE compared to placebo (PL). Twenty-one hypertensive postmenopausal women were randomized to 4 weeks of CIT (10g/day, n=10) or PL ( n=11). Superficial femoral macro- (flow-mediated dilation; FMD) and microvascular function (5s average peak blood velocity and flow during reperfusion) were assessed by ultrasound at 0 and 4 weeks. Femoral artery BF and vascular conductance (VC) were measured via ultrasound at rest and during 3-minute stages of rhythmic PFE at 5%, 15%, and 30% of 1-repetition maximum (1RM) at 0 and 4 weeks. BF and VC responses to PFE were analyzed as the change from rest to the last minute of each stage. There were no differences between groups in FMD, 5s peak velocity and flow during reperfusion, and vascular responses to PFE at 0 weeks. CIT significantly increased FMD (CIT:Δ1.28 ± 0.42 vs PL:Δ0.01 ± 0.40%, p = 0.04) and 5s peak velocity (CIT:Δ17.44 ± 4.21 vs PL:Δ0.09 ± 4.01 cm/s, p = 0.01) and flow (CIT:Δ220 ± 54 vs PL:Δ35 ± 51 mL/min, p = 0.02) during reperfusion compared to PL. CIT had no effect on BF and VC responses to 5% PFE ( p > 0.05). CIT significantly augmented BF responses to 15% PFE (CIT:Δ82 ± 16 vs PL:Δ22 ± 15 mL/min, p < 0.01) and 30% PFE (CIT:Δ156 ± 33 vs PL:Δ38 ± 32 mL/min, p < 0.01) and VC responses to 15% PFE (CIT:Δ0.80 ± 0.16 vs PL:Δ0.11 ± 0.15 mL*100mmHg/min, p < 0.01) and 30% PFE (CIT:Δ1.49 ± 0.29 vs PL:Δ0.24 ± 0.27 mL*100mmHg/min, p < 0.01) compared to PL. Improvements in FMD were not correlated with BF or VC responses to PFE ( p > 0.05). Improvements in 5s peak velocity were positively correlated with BF responses to 15% PFE ( r = 0.498, p = 0.02) and 30% PFE ( r = 0.532, p = 0.01), and with VC responses to 15% PFE ( r = 0.542, p = 0.01) and 30% PFE ( r = 0.633, p < 0.01). Similarly, augmented 5s flow was positively correlated with BF ( r = 0.461, p = 0.04) and VC ( r = 0.558, p = 0.01) responses to 30% PFE. These findings indicate that CIT improved superficial femoral artery macro- and microvascular endothelial function at rest. However, only improvements in microvascular endothelial function influenced vascular function during leg exercise in hypertensive postmenopausal women. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

A Biomechanical Comparison of the Back Squat and Hexagonal Barbell Deadlift.

Stahl, CA, Regni, G, Tanguay, J, McElfresh, M, Trihy, E, Diggin, D, and King, DL. A biomechanical comparison of the back squat and hexagonal barbell deadlift. J Strength Cond Res 38(5): 815-824, 2024-Coaches often use different exercises to encourage similar strength adaptations and limit monotony. Anecdotally, the hexagonal barbell deadlift (HBD) exhibits similarities to the back squat (BS). To date, research has not examined the empirical differences between these exercises. This study examined kinematic and kinetic differences between the BS and the HBD across different loads. Sixteen resistance-trained individuals (6 men and 10 women) volunteered to participate. Subjects performed 1-repetition maximum (1RM) testing under BS and HBD conditions. Kinematic and kinetic data were collected during performance of both exercises at submaximal (warm-up sets) and maximal (1RM) loads using a 3D motion capture and force-plate system. Results showed that subjects lifted greater 1RM loads in the HBD relative to the BS (p < 0.05; d = -1.75). Kinematic data indicated that subjects exhibited greater maximum forward lean of the trunk and decreased maximum knee flexion while performing the HBD compared with the BS. The BS resulted in higher maximum extension moments at the hip joint than the HBD. Maximum extension moments at the knee joint showed no difference between the exercises. Data suggest that bar design and position facilitate balanced moment arm length at hip and knee joints during performance of the HBD. By contrast, bar position during performance of the BS increases moment arm length at the hip joint, making it a hip-dominant exercise. The present data have implications for the programming of both exercises. Future research should examine differences in muscle-activation strategies between the 2 exercises.

Novel Use of 1-methylhistamine as a Biomarker of the Histamine Response to Exercise

Histamine is released within skeletal muscle during exercise, promoting a sustained post-exercise vasodilation and contributing to adaptive responses to exercise training. Tracking this response is complicated by the short half-life and localization of histamine, requiring invasive methods such as intramuscular microdialysis or arteriovenous catheterization. Surrogates based on regional blood flow to assess post-exercise vasodilation require skilled use of expensive equipment, such as ultrasonography. These approaches may not be available in many research or athletic settings. Therefore, we explored the use of 1-methylhistamine (1-MH), a primary metabolite of histamine, as a novel biomarker of histamine’s release in response to aerobic and resistance exercise. We hypothesized that urinary 1-MH production would increase following exercise and that it would be positively correlated with post-exercise femoral artery blood flow and vascular conductance. Six healthy (1F, 5M; 22±4y; 24.3±1.9 kg·m2) trained participants (VO2peak: 51.8±7.7 ml·kg−1·min−1; back squat 1-repetition maximum, 1-RM: 1.66±0.27 kg·bodyweight−1) completed two exercise sessions separated by 1-wk: Aerobic, 30-min of cycling exercise at 70% VO2peak; Resistance, 6 sets of 10 repetitions of back squat exercise at 70% 1-RM. Femoral artery blood flow and vascular conductance were measured and venous blood samples were obtained before, immediately after, and throughout 2-h of post-exercise recovery. Urine was collected during the 24-h before and 2-, and 24-h post-exercise. Histamine and 1-MH concentrations were measured via high-performance liquid chromatography. Results are presented as mean ± SD and were compared by repeated-measures ANOVA and Pearson’s correlations. Blood flow increased immediately after exercise vs before (Aerobic: 442±60 vs 184±58 mL·min−1, p&lt;0.05; Resistance: 626±190 vs 194±54 mL·min−1, p&lt;0.05) and remained elevated 30-min into recovery (Aerobic: 273±63, p&lt;0.05; Resistance: 396±99 mL·min−1, p&lt;0.05). The area under the curve for blood flow after exercise tended to be greater following resistance (16117±5504 mL) vs aerobic (8732±5360 mL, p=0.06) exercise. When averaged across exercise modes, urine 1-MH production was elevated 2-h post-exercise vs before (23.6±15.9 vs 9.2±5.9 μg/h, p&lt;0.05). Urine 1-MH production tended to correlate with percent elevation in femoral artery blood flow (r=0.59, p=0.09) and correlated with the percent elevation in vascular conductance following exercise (r=0.53, p&lt;0.05). These results demonstrate that both aerobic and resistance exercise elicit a histamine response and support the utility of urinary 1-MH production as a biomarker of histamine’s release in response to exercise. Supported by NIH grant R01 AG072805. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

IT’S NEVER TOO LATE TO START: A CASE FOR PREVENTATIVE OUTPATIENT GERIATRIC SERVICES

INTRODUCTION &amp; AIMS The population is ageing and the chronic disease burden growing, seeing more older adults present to hospital with preventable non-communicable diseases. Multidisciplinary outpatient teams are well placed to manage modifiable risk factors to prevent disease progression and hospitalisations. A preventative service was launched at Concord Hospital integrating geriatrician, exercise physiologist and dietitian care to optimise the physical and mental health of older adults with chronic disease and frailty. This evaluation aims to determine the success of service implementation and feasibility of the model. METHODS Between November 2022 and June 2023, 59 patients (mean age 80.2 years (SD 6.2), 47.5% female) completed 12-weeks of concurrent exercise and diet interventions with medical oversight. Patients were assessed pre- and post-interventions. Exercise was individualised and multimodal, performed twice weekly in a supervised group. Diet was individualised with a protein supplement prescribed as appropriate. The outcomes measured were Fried Frailty Phenotype (FFP), leg strength (one repetition maximum leg press), Short Physical Performance Battery (SPPB), Geriatric Depression Scale Short Form (GDS), and Mini Nutritional Assessment Long Form (MNA). Service activity was measured monthly via rate of referral and occasions of service (OOS). Data were analysed using JASP (v.0.18.1). RESULTS Monthly rate of referral and OOS increased from 18 to 51 patients and 49 to 479 occasions respectively, indicating service demand. After 12-weeks there were significant improvements in FFP (mean difference [95%CI] -0.4 [-0.7, -0.2] points), leg strength (34.0 [27.1, 40.8] kilograms), SPPB (1.1 [0.8, 1.5] points), GDS (-1.4 [-2.2, -0.6] points) and MNA (2.6 [1.6, 3.5] points), with no effect of sex observed. CONCLUSION Initial implementation of a preventative outpatient geriatric service was successful with increasing service demand and significant physical and mental health improvements. The service model is feasible; however, further evaluation is required to determine outcomes after continued service provision.

The effect of chronic leg press exercises on hamstring muscle length and different vertical jump performance

Background and Study Aim. As it is known, chronic resistance exercises cause limitations in some joints and this negatively affects the normal range of motion. In the present study, it was aimed to analyse the quadriceps-hamstring balance by analysing different vertical jump performances after six weeks of leg press exercise. Material and Methods. Eleven university students aged between 18-30 years were included in this study. The hamstring muscle length, 1 repetition maximum (1-RM) leg press performance were analysed before and after six weeks of leg press exercise. In addition, the vertical jump performances of the participants were analysed with My Jump 2 software programme. In this study, counter movement jumps (CMJ) and squat jump (SJ) performances of the participants were determined. Results. According to the findings, 1 repetition maximum (1-RM) leg press performance and hamstring length of the participants improved significantly (t=-7.609, ES: -2.29, p&lt;.001; t=-2.540, -0.76, p=.029, respectively). CMJ and SJ parameters of the participants did not change (p&lt;0.05). It was concluded that the lengthened hamstring length after the leg press exercise programme had a positive relationship with vertical jump height (r=0.656, p=0.028), flight duration (r=0.663, p=0.026), speed (r=0.657, p=0.028), and average speed (r=0.669, p=0.024). These relationships were observed among CMJ parameters following the exercise programme. Likewise, a positive correlation was found between hamstring length, which lengthened after the leg press exercise programme, and vertical jump height (r=0.625, p=0.040), flight duration (r=0.646, p=0.032), speed (r=0.646, p=0.032), and average speed (r=0.637, p=0.035). These correlations were identified among the SJ parameters after the exercise. Conclusions. As a result, it was determined that chronic leg press exercises positively affected hamstring muscle length and muscle strength. Different vertical jump performances such as CMJ and SJ did not change. However, the relationship between hamstring length and vertical jump parameters is interesting.

Comparative analysis of two strength training protocols on throwing speed in women's handball

Shooting represents a fundamental skill in handball. Among other factors, its effectiveness requires a significant development of explosive strength. Isometric training may provide a powerful neuromuscular stimulus for its enhancement. Despite its importance and practicality, few studies have addressed the effect of this type of training on shooting speed in women's handball. Twenty female players were divided into two groups: isometric training (GI, n=10) and dynamic training (GD, n=10). Over nine weeks, twice a week, both groups completed an upper limb pushing resistance training: GI performed maximum isometric strength, and GD performed dynamic strength at 80% of one maximum repetition (1MR). In both cases, the effort was followed by medicine ball throws. The loads for both groups were equated in terms of sets and duration. Pre- and post-intervention, the 1MR of each player was estimated through a load progression test in bench press exercise. Additionally, the shooting speed with and without aiming at a target was measured from seven and nine meters using a radar. The findings showed a trend towards improvement in both groups (slightly higher in GI); however, only the not-targeted shooting speed from 9 meters in GI reached statistical significance (p &lt; .05). The correlation between 1MR and shooting speed was low to moderate. In summary, both types of training yielded similar results. Given the practical advantages of isometric training, it could be suggested that this training could serve as an effective and practical alternative for enhancing strength and shooting speed in handball. Keywords: Handball, handball shooting, isometric strength training, women's sport.

Task-specific resistance training adaptations in older adults: comparing traditional and functional exercise interventions.

Muscle strength declines ∼3% per year after the age of 70. Resistance training guidelines for older adults are often based on free-weight and machine exercises, which may be inaccessible and lack carryover to activities of daily living. We tested the hypothesis that resistance training adaptations in older adults are task-specific. Thirty adults (8 males, 22 females; mean age = 71 years) were randomly assigned to participate in 6weeks of supervised, high-intensity resistance training (twice per week) utilizing free-weight and machine exercises (traditional) versus functional activities that were overloaded with a weighted vest (functional). Participants were thoroughly familiarized with the exercises and testing prior to beginning the study. Major outcome measures included assessments of functional performance, five-repetition maximum strength, isometric knee extensor force, and quadriceps muscle size. Physical activity and nutrition were monitored. The study results demonstrate that the magnitude of improvement within a given outcome was largely dependent on group assignment, with greater improvements in gait speed and the timed-up-and-go in the functional group, but 2-3× greater five repetition maximum strength improvements for the trap bar deadlift, leg press, and leg extension following traditional resistance training. Both groups showed improvements in isometric knee extensor force and muscle size, suggesting that some aspects of the observed adaptations were generic, rather than specific. Overall, these novel findings suggest that, among older adults, 1) resistance training adaptations exhibit a high degree of task specificity and 2) significant improvements in functional outcomes can be achieved with the use of a weighted vest.

The Effects of Resistance Training Interventions on Weight, Body Mass Index, Body Fat Percentage, and Flexibility in College Students: A Comparison Between Sports and Non-Sports Students

Background. Resistance training is an effective form of exercise that promotes healthy body weight regulation and enhances flexibility. However, discrepancies exist regarding the varying impacts of resistance training based on individuals’ training status across different fitness components, such as body composition and flexibility. Objectives. The primary objective of this study is to assess whether there are significant differences in the outcomes of resistance training responses between trained and untrained groups concerning body composition and flexibility. Materials and methods. This experimental resistance training study involved 60 male students (age = 20.83 ± 0.85 years old) from the same university. The participants were divided into two groups based on their training status: a trained group (S; n = 30) and an untrained group (NS; n = 30). Both groups underwent an identical training regimen, consisting of three sessions per week over a total of four weeks or 12 training sessions. Results. Significant differences were observed in the paired sample T-test analysis between pre-test and post-test results in the untrained group for body weight (t (29) = 7.940, p &lt; 0.001, d = 1.45), body mass index (t (29) = 7.579, p &lt; 0.001, d = 1.38), body fat percentage (t (29) = 9.733, p &lt; 0.001, d = 1.77), and sit-and-reach flexibility (t (29) = -7.714, p &lt; 0.001, d = -1.40). Similarly, the trained group showed significant changes in body weight (t (29) = 2.644, p = 0.013, d = 0.483), body fat (t (29) = 2.561, p = 0.016, d = 0.351), and flexibility (t (29) = -2.543, p = 0.017, d = 0.351), while no substantial difference was found in body mass index (t (29) = 1.925, p = 0.064, d = -0.464). Conclusion. The study found that using resistance training protocols targeting weight reduction with 60-70% of 1 Repetition Maximum (RM) over a one-month intervention period, without stringent calorie restriction, significantly decreased weight and BMI while enhancing flexibility. Notably, regardless of training status disparities, the untrained group demonstrated more expressed improvements compared to the trained group, indicating the influence of training status on response variations to training stimuli.

Combined PNF and myofascial release techniques impair acute strength performance: A randomized controlled cross-sectional study

Background: Numerous strategies can be implemented as preconditioning preparation to increase strength production, including PNF and MFR strategies, however there are still contradictions in the literature regarding competing effects between preconditioning actions and strength perfor-mance, which it becomes plausible to look for the impact is effect on strength resistance perfor-mance. Objective: of the study was to evaluate the acute effects of series of PNF, myofascial release (MFR), or the sum of the methods, on the development of resistance strength in subsequent series of deadlifts. Methods: Eight adults of both sexes (25.4 ± 4.1 years) participated in the study, attend-ing the gym on 7 visits. The first visit consisted of a sample characterization. On the second and third visits, participants performed the maximum repetition Deadlift procedure, from the fourth to seventh visits, they were randomly divided into: a) CTL; b) PNF; c) MFR; d) PNF + MFR. All sessions followed three sets of the Deadlift exercise with 80% RM. Results: The repeated measures ANOVA showed significant differences between the control condition (no intervention) and the PNF inter-vention (p = 0.034) and MFR + PNF (p = 0.047). However, the Control vs. MFR there were no signif-icant differences (p = 0.07), as well as PNF vs. MFR (p = 0.585), and PNF vs. PNF+MFR (p = 0.382). Conclusion: Strength performance was influenced by the PNF method, or associated with MFR, both reducing total work.

Acute Effects of Combining Weight and Elastic Resistance Exercise on Vascular Function in Older Adults.

Prior research has suggested that resistance exercise may result in a temporary decrease in vascular function, as measured by flow-mediated dilation (FMD), among untrained young individuals. However, the immediate impact of combined elastic and weight resistance training on older adults remains insufficiently explored. We assessed vascular function before, after, and 30 min after acute exercise under three resistance conditions to evaluate whether a combination of weight and elastic resistance exercises has an acute effect on vascular function in older adults. Fourteen older adults (65.6 ± 2.9 years) executed three sets of 12 repetitions at 65% of one repetition maximum (1 RM) of the bench press (BP) exercise. Testing was performed on three separate days as follows: (1) barbell alone (BA); (2) barbell plus elastic bands (10% of 65% 1 RM) (BE10); and (3) barbell plus elastic bands (20% of 65% 1 RM) (BE20). A two-way (time × condition) repeated measures analysis of variance was employed to assess the time and condition effects on flow-mediated dilation (FMD) and pulse wave velocity (PWV). At 0 min post-exercise, FMD was significantly higher during BE10 than during BA (p < 0.05); however, at 30 min post-exercise, no significant difference (p ≥ 0.05) was observed between the three conditions. In each condition, FMD results did not differ significantly at different times (p ≥ 0.05). For FMD, the main effect of the condition (F[2,26] = 3.86, p = 0.034) and that of the time and condition (F[4,52] = 3.66, p = 0.011) were significant. For PWV, only the difference between the BA and BE10 conditions was significant at 0 min (p < 0.05). PWV increased from baseline in the BA condition (p < 0.05) but not significantly in the BE10 and BE20 conditions (p ≥ 0.05). Therefore, BA, BE10, and BE20 demonstrated various changes in vascular function. Long-term training intervention studies are needed to validate these findings.

Inter-Repetition Rest Impact on the Estimated Repetitions in Reserve at Various Loads and Proximities to Neuromuscular Failure.

Ruiz-Alias, SA, Ramirez-Campillo, R, Leando Quidel-Catrilelbún, ME, García-Pinillos, F, and Pérez-Castilla, A. Inter-repetition rest impact on the estimated repetitions in reserve at various loads and proximities to neuromuscular failure . J Strength Cond Res 38(8): 1379-1385, 2024-The repetitions in reserve (RIR) estimation method allows for monitoring resistance training set volume. However, a significant bias is commonly observed when ending the set further from neuromuscular failure and using lower relative loads. Is unclear if implementing an IRR could improve its estimation validity. This study aimed to determine if the RIR estimation is influenced by the IRR at different relative loads and proximities to neuromuscular failure during the back squat (BQ) and bench press (BP) exercises. After a familiarization session, 19 male subjects (age, 21-26 years) completed an experimental session for each IRR configuration: IRR0 (without rest), IRR3 (3 seconds of rest), and SSIRR (self-selected rest [up to 5 seconds]). In each session, single sets to neuromuscular failure were performed at 3 relative loads (65% 1 repetition maximum [1RM], 75% 1RM, 85% 1RM) for BQ and BP exercises. Using the Estimated Repetitions to Failure scale, subjects estimated the RIR associated with a score of "5" and "2" (i.e., RIR-5 and RIR-2). The results revealed no interactions between the RIR estimation and IRR for BQ (RIR-5: p = 0.812; RIR-2: p = 0.084) or BP (RIR-5: p = 0.884; RIR-2: p = 0.944). Subjects provided valid estimations, with overestimation (BQ RIR-5: 0%; BQ RIR-2: 2.9%; BP RIR-5: 1.1%; BP RIR-2: 2.3%) or underestimation (BQ RIR-5: 14.9%; BQ RIR-2: 4%; BP RIR-5: 15.2% BP RIR-2: 8.2%) in few sets. In conclusion, the RIR estimation method seems valid, and the IRR (0-5 seconds) does not influence its validity at 65-85% 1RM loads nor proximities to neuromuscular failure (RIR-2, RIR-5).

Strength and power adaptations of the upper body following 20 training sessions on an eccentric arm-crank ergometer.

Eccentric strength training is an innovative and promising approach to improve exercise performance. However, most eccentric training studies in the past were performed with a focus on the lower extremities. The present study aimed to test the feasibility and effects on strength and power adaptations of a structured upper-body eccentric training program. Fourteen (median age (Q1-Q3) 29years (27-32); 9 females, 5 males) healthy, regularly exercising individuals performed 20 progressive training sessions (2-3 sessions/week at 20-50% peak power for 8-14min) on a symmetric eccentric arm-crank ergometer. Before and after the intervention, anaerobic peak power (PP) and maximal concentric aerobic power output (POmax) on an arm-crank ergometer as well as the one repetition maximum (1RM) for bench press were determined as main outcome parameters. A p-value ≤ 0.05 was considered statistically significant. Significant improvements in PP (+ 4% (1-8), p = 0.007), POmax (+ 6% (0-8); p = 0.01), and 1RM (+ 12% (10-17); p < 0.001) were found. Exercise intensity was relatively low at 64% (55-70) of maximum heart rate. Twenty progressive training sessions on a symmetric arm-crank ergometer are effective in inducing significant aerobic and anaerobic performance and strength improvements in the upper body. This intervention is safe and feasible, and can be performed at relatively low cardiovascular intensities. Therefore, this training method offers an interesting approach from elite sports to rehabilitation.

The Force-Vector Theory Supports Use of the Laterally Resisted Split Squat to Enhance Change of Direction.

Cooley, C, Simonson, SR, and Maddy, DA. The force-vector theory supports use of the laterally resisted split squat to enhance change of direction. J Strength Cond Res 38(5): 835-841, 2024-The purpose of this study was to challenge the conventional change of direction (COD) training methods of the modern-day strength and conditioning professional. A new iteration of the modified single-leg squat (MSLS), the laterally resisted split squat (LRSS), is theorized to be the most effective movement for enhancing COD performance. This study lays out a rationale for this hypothesis by biomechanically comparing the LRSS, bilateral back squat (BS), and MSLS with a COD task (90-degree turn). One repetition maximum (1RM) for LRSS, MSLS, and BS was measured for 23 healthy active female subjects. Peak ground reaction forces (GRF) for the dominant leg were recorded when performing COD and the LRSS, MSLS, and BS at 70% 1RM. Peak frontal plane GRF magnitude and angle were calculated for each task and submitted to repeated measures ANOVA. Peak GRF magnitude was significantly larger for COD (2.23 ± 0.62 body weight) than the LRSS, MSLS, and BS (p ≤ 0.001). Peak GRF angle was not significantly different between COD and the LRSS (p = 0.057), whereas the MSLS and BS (p < 0.001) vector angles were significantly greater than COD. In this application of the force-vector theory, the LRSS more closely matches COD than the MSLS or BS. Thus, the LRSS has the greater potential to enhance COD.

Full-body resistance training promotes greater fat mass loss than a split-body routine in well-trained males: A randomized trial.

While significant progress has been made in understanding the resistance training (RT) strategy for muscle hypertrophy increase, there remains limited knowledge about its impact on fat mass loss. This study aimed to investigate whether full-body is superior to split-body routine in promoting fat mass loss among well-trained males. Twenty-three participants were randomly assigned to 1 of 2 groups: full-body (n=11, training muscle groups 5days per week) and split-body (n=12, training muscle groups 1day per week). Both groups performed a weekly set volume-matched condition (75 sets/week, 8-12 repetition maximum at 70%-80 % of 1RM) for 8weeks, 5days per week with differences only in the routine. Whole-body and regional fat were assessed using DXA at the beginning and at the end of the study. Full-body RT elicited greater losses compared to split-body in whole-body fat mass (-0.775±1.120kg vs. +0.317±1.260kg; p=0.040), upper-limb fat mass (-0.085±0.118kg vs. +0.066±0.162kg; p=0.019), gynoid fat mass (-0.142±0.230kg vs. +0.123±0.230kg; p=0.012), lower-limb fat mass (-0.197±0.204kg vs. +0.055±0.328kg; p=0.040), and a trend in interaction in android fat mass (-0.116±0.153kg vs. +0.026±0.174kg; p=0.051), with large effects sizes (η2 p≥0.17). This study provides evidence that full-body is more effective in reducing whole-body and regional fat mass compared to split-body routine in well-trained males.

The Effect of Sex and Different Repetition Maximums on Kinematics and Surface Electromyography in the Last Repetition of the Barbell Back Squat.

During the ascent phase of a maximal barbell back squat after an initial acceleration, a deceleration region occurs as the result of different biomechanical factors. This is known as the sticking region. However, whether this region is similar in the last repetition of different repetition maximums and if sex has an impact on biomechanics of this region are not known. Therefore, this study investigated the effect of sex (men/women) and repetition maximum (1-, 3-, 6-, and 10RM) on kinematics and surface electromyography around the sticking region. Twenty-six resistance-trained individuals comprising 13 men (body mass: 82.2 ± 8.7; age: 23.6 ± 1.9; height: 181.1 ± 6.5) and 13 women (body mass: 63.6 ± 6.6; age: 23.9 ± 4.5; height: 166.0 ± 4.5) participated in the study. The main findings were that women, in comparison to men, displayed larger trunk lean and lower hip extension angles in the sticking region, possibly due to different hip/knee extensor strength ratios. Moreover, an inverse relationship was discovered between repetition range and timing from V0 to Vmax2, in which lower repetition ranges (1- and 3RM) were shorter in Vmax2 compared to higher ranges (6- and 10RM). It was concluded that this occurrence is due to more moments of inertia in lower repetition ranges. Our findings suggest that both sex and repetition range might induce different requirements during the squat ascent.

Resistance Training to Muscle Failure with Variable Load Intensities: Implications for Post-Exercise Blood Pressure and Heart Rate Variability in Trained Men.

Background: The modulation of cardiac sympathovagal balance alters following acute resistance training (RT) sessions. Nevertheless, the precise influence of RT at varying load intensities on this physiological response remains to be fully elucidated. Therefore, the aim of this study was to compare the time course of recovery following low- (40%), moderate- (60%), and high- (80%) load-intensity RT protocols performed up to muscle repetition failure in resistance-trained men. Method: Sixteen young, resistance-trained men (mean age: 21.6 ± 2.5 years, mean height: 175.7 ± 8.9 cm, mean weight: 77.1 ± 11.3 kg) participated in a randomized crossover experimental design involving three sessions, each taken to the point of muscle failure. These sessions were characterized by different load intensities: low (40% of 1-repetition maximum, 1RM), moderate (60% of 1RM), and high (80% of 1RM). The exercise regimen comprised four exercises-back squat (BS), bench press (BnP), barbell row (BR), and shoulder press (SP)-with each exercise consisting of three sets. Throughout each session, heart rate variability (HRV) and blood pressure (BP) parameters were assessed both pre-exercise and during a 40 min post-exercise period, segmented into 10 min intervals for stabilization. Statistical analysis involved the use of a repeated measures ANOVA. Results: It was observed that the 40% and 60% RT sessions resulted in a significantly higher root mean square of successive R-R intervals (RMSSD) value compared to the 80% RT session in the post-exercise recovery process in 30 min (respectively, p = 0.025; p = 0.028) and 40 min (respectively, p = 0.031; p = 0.046), while the 40% and 60% RT sessions produced similar responses. The 40% RT session was significantly higher in the high frequency (HF) value post-exercise in 40 min compared to the 80% RT session (p = 0.045). Conclusions: Our findings suggest that engaging in resistance training (RT) sessions to muscle failure at an intensity of 80% induces acute increases in sympathetic activity, potentially leading to elevated cardiovascular stress. For individuals with normal blood pressure, it is advisable to opt for lighter loads and higher repetition volumes when prescribing RT, as heavier-load RT may carry an increased risk of cardiac-related factors.

The Role of Physical Fitness on FRAN CrossFit® Workout Performance

The purpose of this study was to investigate the role of physical fitness on the FRAN CrossFit® workout time-trial. Twenty male athletes were divided into a fast group (FG) and a slow group (SG) according to the median value of the FRAN time-trial. Measurements included the FRAN time-trial, body composition analysis, isometric handgrip and isometric mid-thigh pull strength, countermovement jump (CMJ), 30 s continuous jumping test (CJ30), and one repetition maximum (1-RM) strength in the squat, thrusters, snatch, clean and jerk, and dead-lift. The FG had significantly lower body fat (p &lt; 0.018), higher CMJ (p &lt; 0.05), lower percentage decrement in CJ30 height (p = 0.023), and higher 1-RM strength (p &lt; 0.05) compared to the SG. A significant correlation was found between the FRAN time-trial with percentage body fat (r = 0.512, p = 0.021) and with percentage decrement in CJ30 height (r = 0.454, p = 0.044). Performance in the FRAN time-trial was also correlated with CMJ variables (r ranged from 0.634 to 0.663, p &lt; 0.05) and 1-RM strength (r ranged from 0.510 to 0.701, p &lt; 0.05). These results suggest that the FG has a higher tolerance to fatigue and is stronger, more powerful, and has less body fat compared to the SG. Consequently, body fat, 1-RM strength, power, and anaerobic capacity may predict the FRAN time-trial in CrossFit® athletes.

Braking and Propulsion Phase Characteristics of Traditional and Accentuated Eccentric Loaded Back Squats.

The purpose of this study was to examine the differences in braking and propulsion force-time characteristics and barbell velocity between traditional (TRAD) and accentuated eccentric loaded (AEL) back squats using various load combinations. Sixteen resistance-trained men participated in four separate testing sessions which included a one repetition maximum (1RM) back squat during the first session and three squat testing sessions. During the squat testing sessions, participants either performed sets of three repetitions of TRAD back squats each with 50, 60, 70, and 80% 1RM or performed the same loads with the addition of weight releasers that increased the total eccentric weight of the first repetition of each set to either 100 (AEL-MAX) or 110% 1RM (AEL-SUPRA). Braking and propulsion mean force, duration, and impulse as well as mean and peak barbell velocity were compared between each condition and load. Significantly greater braking impulses were produced during the AEL-MAX and AEL-SUPRA conditions compared to TRAD (p < 0.03) with small-moderate effect sizes favoring AEL-SUPRA. No other significant differences existed among conditions for other braking, propulsion, or barbell velocity variables. AEL-MAX and AEL-SUPRA back squats may provide a greater braking stimulus compared to TRAD squats; however, the propulsion phase of the movement does not appear to be impacted. From a loading standpoint, larger and smaller load spreads may favor rapid and maximal force production characteristics, respectively. Further research on this topic is needed as a large portion of the braking stimulus experienced during AEL back squats may be influenced by relative strength.

Effects of Eccentric Speed during Front Squat Conditioning Activity on Post-activation Performance Enhancement of Hip and Thigh Muscles.

The phenomenon of post-activation performance enhancement plays an unidentified role in movement eccentric speed and individual muscle group responses. Therefore, this study aimed to determine whether the loaded front squat (FSq) speed of the eccentric phase would influence the post-activation performance enhancement effect and whether the FSq would elicit similar performance enhancement of knee flexion, knee extension, hip flexion, and hip extension muscles. Twenty resistance-trained handball players performed the FSq under maximum eccentric-concentric speed and 2-s eccentric speed (only the eccentric phase performed), while pre- and post-front squat countermovement jump, knee, and hip isokinetic flexion/extension performance were tested. The FSq conditioning activity was performed in a single set of three repetitions with either 90% (maximum eccentric-concentric speed) or 120% (2-s eccentric speed) of one repetition maximum, and post-performance was measured 4-12 min after the FSq. Athletes randomly changed the FSq eccentric speed and tested the hip or knee isokinetic flexion/extension strength at 180°/s. ANOVA showed that the rate of force development during the jump increased (Cohen d = 0.59-0.77) with no differences between 2-s eccentric and maximum speed eccentric protocols. Isokinetic strength increased after the 2-s eccentric FSq in hip extension (d = 0.76-0.86), knee flexion (d = 0.74-0.88), and hip flexion (d = 0.82), with no differences in knee extension strength. After maximum eccentric-concentric speed, isokinetic strength increased in hip extension (d = 1.25). In conclusion, the FSq conditioning activity enhances hip extensors' performance more than knee extensors' performance. Different eccentric types of muscle action during a conditioning activity alter the level of local muscle enhancement.