Single-joint Exercises Research Articles

Transfer of Muscle Strength Between Single-Joint and Multi-Joint Exercises for Lower Limbs

Most strength and conditioning coaches deal with the question in the training plan, how to supplement specific exercises, or which non-specific exercises would be the most suitable for achieving the set purpose. This study aims to assess what strength transfer with a focus on the lower limbs is projected from the selected strength intervention program (the right leg exercises only single-joint exercises: leg extension on machine and leg curl; the left leg exercises only multi-joint exercises: deadlift and leg press) to the force of the knee joint flexors and extensors during the eccentric and the concentric contraction. In one training session, the participants repeated every exercise five times in four series. The load intensity was around 90% of 1RM and was increased by 5% after the first and the fifth week. The rest interval was always three minutes long. For the left lower limb, the highest transfer (0.20) was from the leg press to the knee joint extensor at the eccentric contraction and from the deadlift was the highest transfer (0.19) to the knee joint extensor at the eccentric contraction. For the right lower limb, the highest transfer (0.53) was from the leg extension on a machine to the knee joint flexor at the concentric contraction and from the lying leg curl was the highest transfer (0.47) to the knee joint flexor at the concentric contraction.

Influence of Adding Single-Joint Exercise to a Multijoint Resistance Training Program in Untrained Young Women.

Barbalho, M, Gentil, P, Raiol, R, Fisher, J, Steele, J, and Coswig, V. Influence of adding single-joint exercise to a multijoint resistance training program in untrained young women. J Strength Cond Res 34(8): 2214-2219, 2020-The aim of the present study was to investigate the effects of adding single-joint (SJ) exercises to a multijoint (MJ) resistance training (RT) program on muscle strength and anthropometric measures of young women. Twenty untrained women were divided into a group that performed only MJ exercises or a group that performed both SJ and MJ exercises (MJ + SJ). Before and after 8 weeks of training, the participants were tested for 10 repetition maximum (10RM). Flexed arm circumference and triceps and biceps skinfold thickness were also measured. Both groups significantly decreased biceps (-3.60% for MJ and -3.55% for MJ + SJ) and triceps skinfold (-3.05% for MJ and -2.98% for MJ + SJ), with no significant difference between them. Flexed arm circumference significantly increased in both groups; however, increases in MJ + SJ (4.39%) were significantly greater than MJ (3.50%). Increases in 10RM load in elbow extension (28.2% for MJ and 28.0% for MJ + SJ), elbow flexion (29.8% for MJ and 28.7% for MJ + SJ), and knee extension (26.92% for MJ and 23.86% for MJ + SJ) were all significant and not different between groups. The results showed that adding SJ exercises to an MJ RT program resulted in no additional benefits in muscle performance, whilst differences in flexed arm circumference were small, but significant, in untrained women.

Strengthening Knee Extensor Muscles In Healthy Individuals: Single-joint Or Multi-joint Exercises?

INTRODUCTION: Increases in muscle strength from resistance training are maximized when the spatiotemporal recruitment of the muscle is full and the peripheral perturbation is high. During maximal single-joint knee extension and multi-joint leg extension movements, activation of the vastii knee extensor muscles is similar, however, little is known of the magnitude and etiology of fatigue development when these movements are repeated. PURPOSE: To compare the magnitude and etiology of fatigue in the vastii knee extensor muscles following repeated maximal contractions performed through single-joint (knee extension) or multi-joint (leg extension) exercises. METHOD: On separate days, 16 participants completed 60 maximal unilateral: i) knee extensions on a dynamometer (KEXT) or ii) leg extensions on a cycle ergometer (LEXT). Knee range of motion (~120° - 30° flexion) and angular velocity (~80°.s-1) were matched. Maximal torque, vastii muscle EMG and M-wave amplitude (Mmax) were calculated during the first and last three contractions of both exercises. Knee extensor isometric maximal voluntary force (IMVF), voluntary activation (VA) and resting twitch force (RT10:100 HZ) were measured pre-exercise and 40-s post-exercise. RESULTS: Similar torque (KEXT: 152 ± 33 N·m vs. LEXT: 165 ± 30 N·m, P > 0.05), EMG (KEXT: 95 ± 6 % vs. LEXT: 96 ± 8 %, P > 0.05) and Mmax (KEXT: 95 ± 5 % vs. LEXT: 97 ± 5 %, P > 0.05) were measured at the start of the exercises. Larger reductions in torque (KEXT: -60 ± 10% vs. LEXT: -38 ± 14%) and EMG (KEXT: -21 ± 16% vs. LEXT: -13 ± 16%) were seen for KEXT during the final part of the exercise (P ≤ 0.05), whereas no differences were reported in Mmax (P > 0.05). Larger reductions in VA were seen after KEXT whereas greater reductions in RT10:100 HZ were seen after LEXT (both P ≤ 0.05). Ultimately, similar reductions in IMVF were seen following KEXT (-32 ± 10%) and LEXT (-35 ± 13%) (P > 0.05). CONCLUSION: A lower-limb resistance training program which adopts multi-joint exercises may induce superior strength gains in vastii knee extensor muscles compared to single-joint exercises, as it is possible to induce larger levels of peripheral fatigue with a smaller reduction in voluntary activation.

Training specificity performing single-joint vs. multi-joint resistance exercises among physically active females: A randomized controlled trial.

Resistance-training of the lower limbs can be performed using exercises moving one (single-joint exercises) or several joints (multi-joint exercises). This study compared the effects of training one multi-joint exercise (leg press) or two single-joint exercises (leg extension and kickback) on dynamic and isometric strength and the transferability of dynamic strength between exercises. Fifty-three physically active women were randomized to a multi-joint (MJ) training group (age = 21.95±0.82 years, mass = 64.85±5.76 kg, height = 167.35±2.47 cm; n = 20), single-joint (SJ) training group (age = 22.56±1.66 years, mass = 64.85±5.76 kg, height = 165.94±2.84 cm; n = 18), or a control (CON) group (age = 21.27±0.68 years, mass = 68.43±4.86 kg, height = 168.63±2.84 cm; n = 15). The training groups participated in an 8-week supervised single- or multi-joint lower limb training consisting of 18 sessions. Pre- and post-training, six repetitions maximum (RM) and maximal voluntary isometric contraction in the three exercises were assessed, along with electromyography of the superficial quadriceps muscles. Improvements in all dynamic exercises were greatest after training the specific exercises (ES = 1.26–2.14, P<0.001–0.025) and all were greater in the training groups than in the CON group (ES = 1.43–3.31, P<0.001–0.021). The SJ group improved 6RM in leg extension and kickback more than leg press (ES = 1.51 and 2.04, respectively, P<0.001), whereas the MJ group improved leg press 6RM more than kickback (ES = 1.10, P = 0.002). However, leg press and leg extension strength improved similarly in the MJ group (ES = 0.54, P = 0.072). All strength and electromyographic measures remained unchanged in the CON group (ES = 0.00–0.44, P = 0.412–0.966). Improved dynamic strength in leg press, kickback and leg extension is best attained by training the specific exercises, but both training modalities can improve strength across all exercises.

The Effects of Resistance Exercise Selection on Muscle Size and Strength in Trained Women.

The study compared the effects of resistance training programs composed by multi-joint (MJ), single-joint (SJ) and the combination of multi- and single-joint (MJ+SJ) exercises on muscle strength and hypertrophy in trained women. Thirty participants were divided into groups that performed only MJ exercises, SJ exercises and MJ+SJ exercises for six months. Participants were tested for 1-repetition maximum (RM) and muscle thickness (MT) before and after the intervention. All groups showed significant gains on 1RM tests from pre- to post-training (P<0.01). However, MJ and MJ+SJ groups obtained greater gains in 1RM for the MJ exercises in comparison with the SJ group. Increases in 1RM for the SJ exercises were similar among groups, with the exception of leg curl, where the SJ group obtained greater gains than MJ and MJ+SJ. All groups obtained significant increases in MT from pre- to post-training for all muscle groups. However, MJ and MJ+SJ groups presented greater increases in gluteus maximus, quadriceps femoris and pectoralis major in comparison with the SJ group. Therefore, our results suggest that, in general, performing MJ exercises seems to be necessary to obtain optimal results from a resistance training program; however SJ might be necessary to provide optimal strength gains in knee flexion.

The effects of exercise order during resistance training on muscular strength

The objective of this study was to compare the muscular strength adaptation during resistance training performed through two methods of exercise order. Thirty recreationally active, resistance untrained men were recruited as research participants and were divided into three groups based on their specific tasks to be performed during six weeks training intervention; i) order A (multi-joint followed by single-joint exercises) ii) order B (single-joint followed by multi-joint exercises) and iii) control group. Bench press was performed as multijoint while chest fly was performed as single-joint exercises. 1RM value for bench press and chest fly exercises were measured pre and post training intervention as an indicator for muscular strength adaptation. Repeated measure analysis of variances (ANOVA) was conducted to determine the effects of training intervention in each groups. The percentages of 1RM score changes during the post test was compared between all groups using one way ANOVA. Results showed that both order A and order B groups improved their 1RM value for both exercises. Bench press 1RM was found to be greater in order A group. Findings of this study suggested that performing a multi-joint exercise first promote greater gain for the multijoint exercise while performing single-joint exercise first lead to no differences in single joint exercise strength gain.

The effects of interset rest duration on performance and muscle activation during resistance training

The purpose of this study was to compare the effects of different rest intervals on performance and muscle activation during multi-joint (bent over row) and single-joint (biceps curl) exercises. Fifteen trained men that have experienced at least one year in resistance training were instructed to perform both exercises using three protocols in a randomized crossover design; each consisting of three sets with three different rest intervals; i) 60 seconds, ii) 90 seconds and iii) 120 seconds rest interval between sets. Each set was performed with hypertrophy designed loading (75% of 1RM) until fatigue. Results showed performing bent over row with 120 seconds rest interval produced higher number of repetitions and greater latissimus dorsi muscle activation compared to 60 seconds and 90 seconds rest interval. For biceps curl exercise, results showed 90 seconds and 120 seconds rest interval produced higher number of repetitions and greater biceps brachii muscle activation compared to 60 seconds rest interval. In conclusion, performing bent over row with 120 seconds rest interval interset and 90 seconds and 120 seconds rest interval during biceps curl exercise allow participants to produce greater lifting performance while recruiting more motor unit for activating the muscles in every set. The findings of this study is hoped to be used as a guideline for resistance training design planning in order to achieve optimum benefit while been time-effective.

Resistance Exercise Order Does Not Affect the Magnitude and Duration of Postexercise Blood Pressure in Older Women.

Tomeleri, CM, Nunes, JP, Souza, MF, Gerage, AM, Marcori, A, Iarosz, KC, Cardoso-Júnior, CG, and Cyrino, ES. Resistance exercise order does not affect the magnitude and duration of postexercise blood pressure in older women. J Strength Cond Res 34(4): 1062-1070, 2020-The aim of this study was to compare the effects of 2 resistance exercise order on postexercise blood pressure (BP) in trained nonhypertensive older women. Sixteen women (68.3 ± 3.3 years, 63.5 ± 11.6 kg, 157.5 ± 5.1 cm) performed 2 sessions with 8 exercises (3 sets of 8-12 repetitions) in distinct orders (from multi- to single-joint exercises [MS] or from single- to multijoint exercises [SM]) and a control session (CS), without exercise. Blood pressure and heart rate (HR) were obtained pre- and postsessions (60 minutes). Postexercise hypotension was observed for systolic BP (SBP) and mean BP in both the MS session (SBP: -6.9 mm Hg, mean BP: -3.3 mm Hg, p ≤ 0.05) and SM session (SBP: -4.6 mm Hg; mean BP: -1.1 mm Hg). Postexercise HR was higher than presession values until 30 minutes of recovery in both training sessions. Furthermore, SBP and mean BP, and HR were lower than the values obtained in the CS (30-60 minutes and 0 minutes, respectively; p ≤ 0.05). There were no differences between the SM and MS sessions in any variable or at any moment. In conclusion, resistance exercise order does not interfere in the magnitude and duration of postexercise hypotension in trained nonhypertensive older women.

Varying the Order of Combinations of Single- and Multi-Joint Exercises Differentially Affects Resistance Training Adaptations

Brandão, L, de Salles Painelli, V, Lasevicius, T, Silva-Batista, C, Brendon, H, Schoenfeld, BJ, Aihara, AY, Cardoso, FN, de Almeida Peres, B, and Teixeira, EL. Varying the order of combinations of single- and multi-joint exercises differentially affects resistance training adaptations. J Strength Cond Res 34(5): 1254-1263, 2020-Our study aimed to compare the effects of multi-joint (MJ) and single-joint (SJ) exercises, either isolated or in combination, and in different orders, on cross-sectional area (CSA) of the pectoralis major (PM) and different heads of the triceps brachii (TB), as well as on the one-repetition maximum (1-RM) in the bench press and lying barbell triceps press. Forty-three young men were randomly assigned to one of 4 possible RT protocols: barbell bench press plus lying barbell triceps press (MJ + SJ, n = 12); lying barbell triceps press plus barbell bench press (SJ + MJ, n = 10); barbell bench press (MJ, n = 10); or lying barbell triceps press (SJ, n = 11). Results showed significant within-group increases in 1-RM bench press for MJ, MJ + SJ, and SJ + MJ but not for SJ. Conversely, significantly greater within-group increases in elbow extension 1-RM were noted for SJ, MJ + SJ, and SJ + MJ but not for MJ. Significantly greater increases in PM CSA were observed for MJ, MJ + SJ, and SJ + MJ compared with SJ. Significant increases in TB CSA were noted for SJ, MJ + SJ, and SJ + MJ, but not for MJ, without observed between-group differences. Individual analysis of TB heads showed significantly greater CSA increases in the lateral head for MJ, MJ + SJ, and SJ + MJ compared with SJ. Alternatively, significantly greater increases in the long head were observed for SJ, MJ + SJ, and SJ + MJ compared with MJ. CSA increases for the medial head were statistically similar between conditions. Our findings indicate that muscular adaptations are differentially affected by performance of MJ and SJ exercises.

Comparison of blood lactate and perceived exertion responses in two matched time-under-tension protocols.

PurposeThe aim of this study was to compare the concentration of blood lactate [bLa-] and the subjective perception of exertion of trained men in a moderate repetition protocol (MRP) versus a high repetition protocol (HRP) equated for time under tension.MethodsA sample of 40 healthy young men (aged, 23.2 ± 4.0 years; height, 177.3 ± 7.0 cm; BMI, 24.3 ± 2.2) performed two sessions of 8 sets of bicep curls with a one-week recovery interval between the trials. In the HRP protocol, 20 repetitions were performed with a cadence of 2 seconds of eccentric and 1 second of concentric, while in the MRP protocol 10 repetitions were performed with 4 seconds of eccentric and 2 seconds of concentric. Cadences were controlled by a metronome. At the beginning and end of each of the sessions, blood lactate was taken at 2, 15, and 30 minutes, and rating of perceived exertion (OMNI-RES) was assessed immediately after completion of each session.ResultsThere were [bLa-] differences between protocols in the MRP 2 min, (5.2 ±1.4); 15 min, (3.2 ±1.2); 30 min, (1.9 ±0.6); p< 0.05, and the HRP 2 min, (6.1 ±1.6); 15 min, (3.7 ±1.1); 30 min, (2.2 ±0.6); p<0.01. OMNI-RES was higher in HRP, (8.8 ±0.7) than in MRP, (7.7 ±0.9). Additionally, a correlation was found between the RPE and [bLa-] values in the HRP protocol (rs = 0.35, p < 0.01).ConclusionsTraining protocols with high times under tension promote substantial increases in metabolic stress, however, our findings indicate that HRP generates more [bLa-] than MRP. In addition, there were higher RPE values in the HRP protocol compared to MRP in single-joint exercises.

Sodium bicarbonate supplementation in resistance exercise performance, perceived exertion and blood lactate concentration

Abstract Aim: The aim was to evaluate the effect of sodium bicarbonate supplementation (NaHCO3) in repetition performance, perceived exertion and blood lactate concentration. Methods: Fourteen trained men (25.14 ± 3.5 years; 85.83 ± 10.18 kg; 1.78 ± 0.06 m; 26.88 ± 3.17 kg/m2) realized two upper-body resistance exercise sessions consisting of 15-RM load and 1 minute of the interval, combining bicarbonate supplementation (BS) or Placebo conditions. Results: After the ANOVA analysis, no difference was found on the total number of repetitions during the session on both BS and Placebo condition (p = 0.11). However, a greater number of total of repetitions on the machine chest fly exercise for BS vs. Placebo condition (p = 0.04) was observed. The perceived exertion increased regardless of the supplementation condition (p < 0.0001). Additionally, for the blood lactate was observed significant increases in BS vs. Placebo condition in the post verification (p = 0.013), corroborated for a bigger area under the curve (AUC) on the BS compared to Placebo (p = 0.026) condition. Conclusion: In conclusion, sodium bicarbonate supplementation was not able to improve performance during a resistance exercise session, except for the single-joint exercise performed with high values of perceived exertion, not altering the perceived exertion, and blood lactate between protocols.

Older Adults Differentially Modulate Transcranial Magnetic Stimulation–Electroencephalography Measures of Cortical Inhibition during Maximal Single-joint Exercise

The effects of muscle fatigue are known to be altered in older adults, and age-related changes in the brain are likely to be a contributing factor. However, the neural mechanisms underlying these changes are not known. The aim of the current study was to use transcranial magnetic stimulation combined with electroencephalography (TMS–EEG) to investigate age-related changes in cortical excitability with muscle fatigue. In 23 young (mean age ± SD: 22 ± 2 years) and 17 older (mean age ± SD: 68.3 ± 5.6 years) adults, single-pulse TMS–EEG was applied before, during and after the performance of fatiguing, intermittent isometric abduction of the index finger. Motor-evoked potential (MEP) measures of cortical excitability were increased during (estimated mean difference, 123.3%; P < 0.0001) and after (estimated mean difference, 117.5%; P = 0.001) fatigue and this was not different between groups (P > 0.5). For TMS–EEG, the amplitude of the P30 and P180 potentials were unaffected by fatigue in older participants (P > 0.05). In contrast, the amplitude of the N45 potential in older adults was significantly reduced both during (positive cluster: mean voltage difference = 0.7 µV, P < 0.005; negative cluster: mean voltage difference = 0.9 µV, P < 0.0005) and after (mean voltage difference = 0.5 µV, P < 0.005) fatiguing exercise, whereas this response was absent in young participants. These results suggest that performance of maximal intermittent isometric exercise in old but not young adults is associated with modulation of cortical inhibition likely mediated by activation of gamma-aminobutyric acid type A receptors.

The Effects of Resistance Exercise Training on Strength and Functional Tasks in Adults With Limb-Girdle, Becker, and Facioscapulohumeral Dystrophies.

Background: The inclusion of resistance training in the treatment and management of muscular dystrophy has previously been discouraged, based on mainly anecdotal evidence. There remains a lack of experimental investigation into resistance training in individuals with muscular dystrophy. The aim of the current study was therefore, to determine the effect of a 12-week resistance training programme on muscle strength and functional tasks in ambulatory adults with muscular dystrophy.Methods: Seventeen ambulatory adults with muscular dystrophy (Facioscapulohumeral muscular dystrophy: n = 6, Limb-Girdle muscular dystrophy: n = 6, Becker muscular dystrophy: n = 5) were recruited for this study. Participants attended three testing sessions: one session at baseline, one session after a 12-week control period and one session after a 12-week resistance training period. Each testing session consisted of measurements of isometric knee extensor and knee flexor maximum voluntary contraction (MVC) torque (Cybex dynamometer). Participants also completed a timed sit-to-stand, a four steps-stair ascent, and a four steps-stair decent. The 12-week resistance training period consisted of two supervised sessions a week. Each training session included a 5-min warm-up, a step-up exercise, free-standing or assisted squats, knee flexion and knee extension exercises, and an additional 6 single-joint exercises specific to each individual's needs.Results: Knee flexor MVC torque increased by 13% after the 12-week resistance training programme (p < 0.05), with no change over the control period. Knee extensor MVC torque did not significantly change after the training programme or the control period. Time taken to complete sit-to-stand, stair ascent and stair descent all decreased (improved) following the 12-week training programme (p < 0.05).Conclusions: A twice-a-week, 12-week, resistance training programme resulted in increased knee flexion strength and improvements in functional tasks in ambulatory adults with muscular dystrophy. This provides support for the inclusion of resistance training in the treatment programmes for these forms of muscular dystrophy.

Bilateral and unilateral load-velocity profiling in a machine-based, single-joint, lower body exercise.

BackgroundTo analyze the goodness of fit of the load-velocity relationship in a machine-based, single-joint exercise performed both in a bilateral and unilateral manner, as well as to study its accuracy to estimate one repetition maximum (1-RM).MethodsFifteen resistance trained males performed an incremental test in the bilateral and unilateral leg extension exercise up to the 1-RM in two separate occasions. Mean vertical velocity of the weight plates in the leg extension machine was measured for every repetition using a smartphone application (My Lift).ResultsLinear regression analyses showed a high goodness of fit (R2 > 0.93) and small standard errors of estimate (SEE < 5%1-RM) both in the bilateral and unilateral leg extension when individual load-velocity regressions for each participant were computed. Unilateral load-velocity relationships showed significant differences in the intercept of the regression line with the Y-axis and the velocity at each percentage of the 1-RM (Cohen’s d > 1.0, p< 0.05). Finally, non-significant differences were observed between actual and estimated 1-RM from the load-velocity relationships (r = 0.88.0–96, Cohen’s d < 0.2, p> 0.05).ConclusionsThis proof of concept highlights that computing load-velocity relationships in a machine-based, single-joint, angular exercise can be appropriately performed by measuring the mean vertical velocity of the weight plates. These results could help strength and conditioning researchers and coaches who wish to analyze load-velocity relationship in other common machine-based exercises.

Different Knee and Ankle Positions Affect Force and Muscle Activation During Prone Leg Curl in Trained Subjects

Marchetti, PH, Magalhaes, RA, Gomes, WA, da Silva, JJ, Stecyk, SD, and Whiting, WC. Different knee and ankle positions affect force and muscle activation during prone leg curl in trained subjects. J Strength Cond Res 35(12): 3322-3326, 2021-Different joint positions for biarticular muscles may affect force and muscular activity during single-joint exercises. The aim of this study was to compare the maximal isometric contractions and muscle activation in 2 different knee and ankle positions during prone leg curl exercise in trained subjects. Fifteen resistance-trained men (27 ± 4 years, 178.80 ± 5.72 cm, 86.87 ± 12.51 kg) were recruited. The peak force (PF) and muscle activation of biceps femoris, gastrocnemius lateralis (GL), and soleus lateralis (SL) were measured during knee flexion at 0 and 90° and maximal dorsiflexion (D) or plantarflexion (P). Three maximal voluntary isometric contractions of 5 seconds were performed for each combination of knee and ankle positions. Two-way repeated-measures analysis of variances were used for all dependent variables. For PF, there was a significant difference between ankle positions (D × P) at 90° (p = 0.009) and knee positions (0 × 90°) for D (p < 0.001) and P (p < 0.001). Peak force was greater with the knee at 0° and the ankle maximally dorsiflexed. For GL, there was a significant difference between ankle (D × P) at 0° (p = 0.002) and knee positions (0 × 90°) for D (p = 0.005). Gastrocnemius lateralis activation was greater with the knee at 90° of flexion and the ankle maximally dorsiflexed. For SL, there was a significant difference between ankle positions (D × P): at 90° (p = 0.001) and at 0° (p = 0.002). Soleus lateralis is more active in plantarflexion irrespective of the knee joint position. Isometric contractions with full knee extension produce more strength regardless of the ankle position; neither the knee position nor the ankle position may influence the activity of the hamstrings.

Calculating Set-Volume for the Limb Muscles with the Performance of Multi-Joint Exercises: Implications for Resistance Training Prescription.

Resistance training volume, determined by the number of sets performed (set-volume) is considered one of the key variables in promoting muscle hypertrophy. To better guide resistance exercise prescription for weekly per-muscle training volume, the purpose of this paper is to provide evidence-based considerations for set-volume ratios between multi-joint (MJ) and single-joint (SJ) exercises so that practitioners can better manage prescription of training volume in program design. We analyzed this topic from three primary areas of focus: (1) biomechanical and physiological factors; (2) acute research; and (3) longitudinal research. From a biomechanical and physiological standpoint, when considering force production of different muscle groups, the moment arm of a given muscle, “motor abundance”, the link between biomechanics and exercise-induced fatigue, as well as the amount of time in voluntary muscle activation, a logical rationale can be made for SJ exercises producing greater hypertrophy of the limb muscles than MJ exercises (at least from specific exercises and under certain conditions). This would mean that sets for a MJ exercise should be counted fractionally for select muscles compared to an SJ exercise (i.e., less than a 1:1 ratio) when prescribing set-volumes for given muscles. When considering results from acute studies that measured muscle activation during the performance of SJ and MJ exercises, it seems that MJ exercises are not sufficient to maximize muscle activation of specific muscles. For example, during performance of the leg press and squat, muscle activation of the hamstrings is markedly lower than that of the quadriceps. These results suggest that a 1:1 ratio cannot be assumed. Current longitudinal research comparing the effects of training with MJ vs. SJ or MJ + SJ exercises is limited to the elbow flexors and the evidence is somewhat conflicting. Until more research is conducted to derive stronger conclusions on the topic, we propose the best advice would be to view set-volume prescription on a 1:1 basis, and then use logical rationale and personal expertise to make determinations on program design. Future research should focus on investigating longitudinal hypertrophic changes between MJ and SJ in a variety of populations, particularly resistance-trained individuals, while using site-specific measures of muscle growth to more systematically and precisely compute effective individualized set-volumes.

Single-Joint Exercise Results in Higher Hypertrophy of Elbow Flexors Than Multijoint Exercise.

Mannarino, P, Matta, T, Lima, J, Simão, R, and Freitas de Salles, B. Single-Joint Exercise Results in Higher Hypertrophy of Elbow Flexors Than Multijoint Exercise. J Strength Cond Res 35(10): 2677-2681, 2021-Recent data suggest that single-joint exercises are unnecessary to maximize the resistance training (RT) results in novice to advanced individuals. However, the present literature is still inconsistent on this topic and controversy arises. The aim of this study was to compare the effects of the unilateral dumbbell row (DR) (multiple-joint) vs. unilateral biceps curl (BC) (single-joint) exercises on strength and elbow flexors muscle thickness (MT). Ten untrained men were assigned to an 8-week RT program for elbow flexors, one arm performing DR and the other performing BC in a within-subject design. After a familiarization, pretraining MT was measured using an ultrasound (US) technique, and strength was tested using 10 repetition maximum (10RM) tests. After pretesting, 8 weeks of RT (4-6 sets, 8-12 repetitions to concentric failure, 2 sessions per week) was performed. Post-testing was conducted in the same order as pretesting 48 and 72 hours after the last session. Single-joint BC exercise resulted in higher hypertrophy of elbow flexors (11.06%) than the DR (5.16%) multijoint exercise after 8 weeks of RT (p = 0.009). The 10RM improvement was higher for DR in DR-trained arm, whereas 10RM for BC was higher in BC-trained arm. The single-joint exercise resulted in higher hypertrophy of the elbow flexors than multijoint exercise after 8 weeks of RT, whereas strength improvements were greater in accordance with specificity of RT exercise. Therefore, in RT prescription for elbow flexors hypertrophy, single-joint exercises such as BC should be emphasized.

Optimal loads for power in older men and women using plate-loaded resistance machines.

Age-related decrements in power affect quality of life in older adults; however, no studies have determined the optimal loads that maximize power outputs using the most commonly employed lifting equipment, plate-loaded machines. Fifteen older men (69.2 ± 6.9 y) and 22 older women (68.9 ± 5.9 y) performed two sessions of strength and power testing. Individuals completed ten plate-loaded exercises to determine their maximum dynamic strengths (1RM) and peak power outputs (PP). Power was tested at 40, 50, 60, 70 and 80% 1RM using a linear position transducer. PP was expressed relative to the highest power produced (PPREL). Multi-joint exercises produced optimal load values at 50-60%1RM for leg press, 50%1RM for chest press, and 40-60%1RM for seated row, with no significant differences among loads for shoulder press. Single-joint exercise optimal loads were seen at 50-60% for hip adduction, 50-70%1RM for calf raise, 60-80%1RM for biceps curl, and 50-80%1RM for triceps extension, with no significant differences between loads for hip abduction or leg curl. No significant differences were found between sexes for any exercise. Different optimal load ranges are required for individual plate-loaded exercises in older persons. Specifically, multi-joint exercises demonstrated a narrow optimal load range favoring the velocity end of the load-velocity curve, while single-joint exercises produced a wider optimal load range extending into the upper limits of the load end of the curve.

Effects Of Rate Of Force Production On Vastus Lateralis Pennation Angle During Isometric Squats And Knee Extensions

Previous literature has shown that force exerted by muscle is closely related to its size, length (i.e. joint angle) and pennation angle (PA). For a mono-articular muscle such as the vastus lateralis (VL), its ability to produce maximal force is dependent on the joint angle of the knee. However, since the VL shares a joint action with a bi-articular muscle, the rectus femoris (RF), it’s possible that its performance may also be affected by the angle of the hip (i.e. the RF contribution to knee extension is hip angle dependent, which may influence VL performance as well). It is unknown how the pennation angle of the VL during contraction differs between maximal multi- and single-joint exercises, such as the isometric squat (SQ) and knee extension (KE), and whether those changes are dependent on the rate of the force production. PURPOSE: To examine the pennation angle of the VL during slow and rapid maximal force production of the isometric SQ and KE exercises. METHODS: Fifteen lower-body resistance trained males (mean ± SD age = 24 ± 3 yrs) performed two separate maximal voluntary contractions (MVC) for both SQ and KE exercises. The first MVC (MVC1) cue was used to elicit peak force, with no instructions on the rate,while the 2nd (MVCR) was used to elicit rapid force production. Knee joint angles were set at 110° during both exercises, while hip angle was ~110° and ~105° during the SQ and KE, respectively. During all MVCs, ultrasonography was used to measure pennation angle of the VL muscle at peak force production. RESULTS: A two-way [MVC speed (slow vs. rapid) × exercise (SQ vs. KE)] repeated measures ANOVA indicated no significant differences in pennation angle of the VL between slow vs. rapid MVCs of the squat (mean MVC1 = 16.19 ± 3.18°, MVCR = 16.13 ± 3.26) and knee extension exercises (mean MVC1 = 16.21 ± 2.23, MVCR = 16.08 ± 2.34), nor were there any differences between the exercises (p > 0.05 for all analyses). CONCLUSION: When knee angle is controlled for, the pennation angle of the VL during isometric squats and knee extensions do not differ. Furthermore, neither the rate of force, nor the slightly different hip angles had an effect.

Effects of strength training with continuous or intermittent blood flow restriction on the hypertrophy, muscular strength and endurance of men

The aim of the present study was to compare the effects of strength training (ST) with continuous or intermittent blood flow restriction (BFR) on the muscle hypertrophy (MH), dynamic muscle strength (DMS), isometric muscle strength (IMS) and localized muscular endurance (LME) of healthy men. Twenty-five men with experience in ST were randomly divided into 3 experimental groups: a) 4 low-load exercises at 20% of the one-repetition maximum (1RM) combined with continuous BFR (LL+CBFR), b) 4 low-load exercises at 20% of 1RM combined with intermittent BFR (LL+IBFR); and c) 4 low-load exercises at 20% of 1RM without BFR (LL). Twelve sessions of ST were performed (twice a week for 6 weeks). There were no differences between groups for all variables (p > 0.05). However, there were significant differences in time for the LME in the triceps pulley only in the LL+CBFR group (p < 0.001) and in the biceps pulley in the groups LL+CBFR, LL+IBFR and LL (p < 0.001, p = 0.002, p = 0.032), respectively, with large magnitudes only for the two forms of the BFR. It can be concluded that continuous or intermittent BFR seems to be a good alternative for the increase of the LME of the upper limbs in single-joint exercises.