Multi-joint Exercises Research Articles

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.

Suspension Training: A New Approach to Improve Muscle Strength, Mass, and Functional Performances in Older Adults?

After the fifth decade of life, the natural aging process leads to annual reductions of 1.5% and 1–2% in muscle strength and mass, respectively (Morley et al., 2014; Zembron-Łacny et al., 2014). Additionally, muscle power is also reduced by 3–4% annually in older subjects (Macaluso and De Vito, 2004). These changes in the neuromuscular system are associated with impairments in functional performance (e.g., motor performance, control, balance, and mobility), increasing morbidity and mortality risks (Frontera et al., 2008; Cruz-Jentoft et al., 2010; Morley et al., 2014; Marty et al., 2017; McGlory et al., 2019). Different resistance training (RT) modes have been proposed as effective interventions for enhancing muscle strength, mass, power, and functional performance in older adults [Chodzko-Zajko et al., 2009; American College of Sports Medicine position stand (ACSM), 2011]. However, less investigated RT modes also appear capable of optimizing these essential adaptations for older adults. Suspension training (ST) is a RT mode in which body segments are attached to suspended hanging straps, creating an unstable environment and using the body weight against gravity to perform multi-planar and multi-joint exercises (Byrne et al., 2014; Mok et al., 2015; Cugliari and Boccia, 2017). Interestingly, ST provides a progressive stimulus in the target muscles and a substantial activation in core muscles, suggesting it could be a promising RT mode to optimize muscle strength, mass, power, and functional performance (Mate-Munoz et al., 2014; Ma et al., 2017). The purpose of this manuscript is to provide rationale as to why ST could be a viable RT mode for increasing muscle strength, mass, power, and functional performance in older adults.

Functional strength exercise and blood-flow restriction protocols: a systematic review

Objective: To assess current literature focused on the influence of functional training with blood flow restriction (BFR) on muscular adaptation in adults below the age of 65 years. Methods: A systematic literature search was performed with the following databases: PubMed, CINAHL Complete EBSCOhost, and ScienceDirect. Two researchers filtered the articles according to the criteria and quality, supported by the Consolidated Standards of Reporting Trials (CONSORT) tool. Studies were limited to those with participants with a mean age between18 and 65 years. Articles were peer-reviewed, available in English, and utilized either multi-joint resistance exercises or functional exercise as the intervention. Results: The search yielded 16 studies on uninjured, older adult, injured and athletic subjects. Regardless of the population, the studies tended to favor BFR training for improvements of strength, but this was highly dependent on cuff pressure and training load. Conclusions: Current literature suggests that BFR with functional and or multi-joint strength training is successful in improving strength, hypertrophy, function and in pain reduction. Favorable results with functional BFR included procedures using relative and well-controlled occlusion pressure. More research is necessary to understand the effect of BFR on self-reported outcomes and hypertrophy in athletic and older adults.

Multi-joint vs Single-joint Resistance Exercises Induce a Similar Strength Increase in Trained Men: A Randomized Longitudinal Crossover Study

Multi-joint vs Single-joint Resistance Exercises Induce a Similar Strength Increase in Trained Men: A Randomized Longitudinal Crossover Study

Effects of cluster training on body composition and strength in resistance-trained men

BACKGROUND: Cluster Training (CL) is an alternative to traditional training where intra-set breaks are incorporated. Positive effects have been reported on sports performance. However, there is little research on body composition in trained subjects. OBJECTIVE: The aim of this study was to investigate the effects of three cluster training (CL) protocols comprised of different intra-set rest (RIntra) and blocks of repetitions (BK) on strength, power and body composition in individuals maintaining a high protein diet. METHODS: Twenty-nine resistance-trained male participants were randomized to RIntra 20 s and BK 3 RM (n= 8, CL1), RIntra 40 s and BK 3 RM (n= 7, CL2), RIntra 20 s and BK 6 RM (n= 7, CL3), and control group (n= 7, CG). All participants performed two sessions per week of lower-limb resistance training for 8 weeks. RESULTS: There were significant changes in FFM in CL1 (0.9 ± 0.5 kg, P= 0.001, ES = 0.17), CL2 (0.6 ± 0.5 kg, P= 0.010, ES = 0.14) and CL3 (0.6 ± 0.4 kg, P= 0.011, ES = 0.14) but not in CG (0.4 ± 1.1 kg, P= 0.323, ES = 0.13). Likewise, significant increases were found in the cluster groups (CL1, 14.5 ± 12.3, P= 0.012, ES = 0.80; CL2, 10.1 ± 4.3, P= 0.001, ES = 0.60; CL3, 9.5 ± 4.9, P= 0.002, ES = 0.45) but not in CG (9.0 ± 9.0, P= 0.057, ES = 0.55). There were no significant changes for any group in CMJ. CONCLUSIONS: We conclude that a RIntra of ∼ 20 s in CL protocols with 3 RM blocks in multi-joint exercises of the lower-limb is sufficient to elicit significant training adaptations; no additional benefits were obtained using longer rest intervals.

The Minimum Effective Training Dose Required to Increase 1RM Strength in Resistance-Trained Men: A Systematic Review and Meta-Analysis.

Increases in muscular strength may increase sports performance, reduce injury risk, are associated with a plethora of health markers, as well as exerting positive psychological effects. Due to their efficiency and effectiveness in increasing total body muscular strength, multi-joint exercises like the powerlifts, i.e.: the squat (SQ), bench-press (BP) and deadlift (DL), are widely used by active individuals as well as athletes in the pursuit of increasing strength. To date, the concept of a minimum dose, i.e. "what is the minimum one needs to do to increase 1-repetition maximum (1RM) strength?" has not been directly examined in the literature, especially in the context of the powerlifts. This review aims to explore the current available evidence around the minimum effective training dose required to increase 1RM strength in trained individuals in an attempt to enhance the practical guidelines around resistance-training as well as provide active individuals, athletes and coaches with more flexibility when designing a training protocol. One reviewer independently conducted the search in a PRISMA systematic approach using PubMed, SportDiscus and Google Scholar databases. The databases were searched with the following search terms/phrases and Boolean operators: "training volume" AND "powerlifting" OR "1RM strength" OR "powerlifters", "low volume" AND "powerlifting" OR "powerlifting" OR "1RM strength", "high vs low volume" AND "powerlifting" OR "1RM strength", "minimum effective training dose 1RM". Meta-analyses were performed to estimate the change in 1RM strength for the lowest dose group in the included studies. From the initial 2629 studies, 6 studies met our inclusion criteria. All identified studies showed that a single set performed minimum 1 time and maximum 3 times per week was sufficient to induce significant 1RM strength gains. Meta-analysis of 5 studies showed an estimated increase for overall 1RM of 12.09kg [95% CIs 8.16kg-16.03kg], an increase of 17.48kg [95% CIs 8.51kg-26.46kg] for the SQ, and 8.25kg [95% CIs 0.68kg-15.83kg] for the BP. All of the included studies contained details on most of the variables comprising "training dose", such as: weekly and per session sets and repetitions as well as intensity of effort. Specific information regarding load (%1RM) was not provided by all studies. The results of the present systematic review suggest that performing a single set of 6-12 repetitions with loads ranging from approximately 70-85% 1RM 2-3 times per week with high intensity of effort (reaching volitional or momentary failure) for 8-12weeks can produce suboptimal, yet significant increases in SQ and BP 1RM strength in resistance-trained men. However, because of the lack of research, it is less clear as to whether these improvements may also be achievable in DL 1RM strength or in trained women and highly trained strength athletes. This systematic review was registered with PROSPERO (CRD42018108911).

Effectiveness of Whey Protein Hydrolysate and Milk-Based Formulated Drinks on Recovery of Strength and Power Following Acute Resistance Exercise.

Intensive resistance exercise can result in exercise-induced-muscle-damage, which commonly leads to reductions in acute muscle function. Post-exercise ingestion of carbohydrate-protein mixtures intends to attenuate these effects. This study aimed to compare the effectiveness of whey protein hydrolysate and milk-based formulated drinks on recovery of muscle function following resistance exercise. Thirty resistance-trained males were randomly assigned to either whey hydrolysate and dextrose drink (WH), milk-based drink (MB) or flavored-dextrose (CHO), and performed baseline assessments of perceived-muscle-soreness, the countermovement jump, the seated-medicine-ball throw and isokinetic assessment of the knee extensors and flexors maximal strength. Subsequently, participants performed resistance exercise consisting of various multi-joint barbell exercises. Following resistance exercise participants then consumed either WH (533 Kcal, 32.6 g Protein, 98.3 g Carbohydrate, 1.1 g Fat), MB (532 Kcal, 32.8 g Protein, 98.4 g Carbohydrate, 0.6 g Fat) or CHO (531 Kcal, 0 g Protein, 132.7 g Carbohydrate, 0 g Fat). All assessments were repeated 24 and 48 h post-resistance exercise. Muscle soreness was markedly increased at 24 h and 48 h in all groups (p < 0.001). However, for dynamic power measures (countermovement jump, seated-medicine-ball throw), CHO experienced a decrease for the countermovement jump only at 48 h, whereas WH and MB experienced significant decreases across the countermovement jump and the seated-medicine-ball throw (p < 0.05). All groups experienced significant decreases in isokinetic-extension torque at both 24 h and 48 h; however, flexion torque was decreased for CHO only at these time points (p < 0.05). Consumption of WH or MB did not enhance recovery of dynamic power-producing ability or soreness compared to CHO. Based on within-group effects WH and MB ingestion had seemingly marginal to small positive effects on recovery of isokinetic strength, however, there were no between-group differences for these variables.

The effects of a 4-week mesocycle of barbell back squat or barbell hip thrust strength training upon isolated lumbar extension strength.

ObjectivesCommon exercises such as the barbell back squat (BBS) and barbell hip thrust (BHT) are perceived to provide a training stimulus to the lumbar extensors. However, to date there have been no empirical studies considering changes in lumbar extension strength as a result of BBS or BHT resistance training (RT) interventions.PurposeTo consider the effects of BBS and BHT RT programmes upon isolated lumbar extension (ILEX) strength.MethodsTrained male subjects (n = 14; 22.07 ± 0.62 years; 179.31 ± 6.96 cm; 79.77 ± 13.81 kg) were randomised in to either BBS (n = 7) or BHT (n = 7) groups and performed two training sessions per week during a 4-week mesocycle using 80% of their 1RM. All subjects were tested pre- and post-intervention for BBS and BHT 1RM as well as isometric ILEX strength.ResultsAnalyses revealed that both BBS and BHT groups significantly improved both their BBS and BHT 1RM, suggesting a degree of transferability. However, the BBS group improved their BBS 1RM to a greater degree than the BHT group (p = 0.050; ∼11.8 kg/10.2% vs. ∼8.6 kg/7.7%, respectively). And the BHT group improved their BHT 1RM to a greater degree than the BBS group (p = 0.034; ∼27.5 kg/24.8% vs. ∼20.3 kg/13.3%, respectively). Neither BBS nor BHT groups significantly improved their isometric ILEX strength.ConclusionsThe present study supports the concept of specificity, particularly in relation to the movement mechanics between trunk extension (including pelvic rotation) and ILEX. Our data suggest that strength coaches, personal trainers, and trainees can self-select multi-joint lower-body trunk extension exercises based on preference or variety. However, evidence suggests that neither the BBS nor BHT exercises can meaningfully increase ILEX strength. Since strengthening these muscles might enhance physical and sporting performance we encourage strength coaches and personal trainers to prescribe ILEX exercise.

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.

Comparison of single- and multi-joint lower body resistance training upon strength increases in recreationally active males and females: a within-participant unilateral training study.

The present study compared strength increases resulting from either single-joint (SJ) or multi-joint (MJ) lower body resistance exercise. A within-participants design was utilised. Ten recreationally active participants (males; n=5, and females; n=5) had their lower limbs randomly allocated to perform both unilateral MJ (leg press; LP) and unilateral SJ (knee extension; KE, and seated knee flexion; KF) exercises. Participants trained 2 d.week-1 for 6 weeks. Pre- and post-intervention maximal strength (1-repetition maximum; 1RM) was measured for leg press, knee extension, and seated knee flexion exercises. Statistically significant strength increases occurred for both SJ and MJ groups, with significantly greater increases in 1RM for the MJ compared to the SJ group (p < 0.001 for all exercises). This study supports the use of MJ exercise for strength increases across lower body MJ and SJ movements, suggesting a time-efficient, and simple approach to resistance training may be efficacious. This might serve to promote greater adherence in the lay population as well as serving useful for rehabilitation professionals and strength and conditioning coaches in managing resistance exercise around skill/sport specific training.

Biomechanical and Functional Outcomes After Medial Patellofemoral Ligament Reconstruction: A Pilot Study

Background:Previous studies have acknowledged the medial patellofemoral ligament (MPFL) as the primary stabilizer of the patella, preventing lateral displacement. MPFL reconstruction (MPFL-R) restores stability and functionality to the patellofemoral joint and has emerged as a preferred treatment option for recurrent lateral patellar instability.Purpose:To objectively measure biomechanical characteristics of athletes cleared for return to sport after MPFL-R compared with healthy controls.Study Design:Cohort study; Level of evidence, 3.Methods:A prospective case-control study design was employed on 31 total athletes. Sixteen athletes (6 male, 10 female; mean age, 16.1 ± 2.74 years; 385 ± 189 days after surgery and 235 ± 157 days after return to sport) underwent MPFL-R and were medically cleared to return to sport. This group was matched by age, sex, and activity level to 15 healthy athletes with no history of lower extremity injuries. Athletes and controls completed validated questionnaires as well as hopping, jumping, and cutting tests with 3-dimensional motion analysis and underwent strength, flexibility, laxity, and balance assessments.Results:Participants in the MPFL-R group scored significantly lower (worse) on the International Knee Documentation Committee (IKDC) (89.2 ± 7.6 vs 98.1 ± 2.0, respectively; P = .0005) and significantly higher (worse) on the Tampa Scale for Kinesiophobia (TSK) (32.4 ± 5.0 vs 25.4 ± 6.5, respectively; P = .006) than those in the control group, but there was no difference in the Kujala score (95.6 ± 5.3 vs 98.8 ± 3.0, respectively; P = .06). Participants in the MPFL-R group demonstrated reduced hip and ankle flexion relative to those in the control group (P < .05). Participants in the MPFL-R group also took significantly longer to complete the 6-m timed hop test relative to those in the control group (P < .05). No statistically significant differences were found in anthropometrics, knee extension or flexion strength, hamstring flexibility, hip abduction strength, or joint laxity between the MPFL-R and control groups.Conclusion:The current data indicate that MPFL-R generally restores functional symmetry, while subtle deficits in global power may remain after being released to full activity. Clinicians should ensure that athletes are fully rehabilitated before returning to sport after MPFL-R by emphasizing functional multijoint exercises.

Asymmetry of force generation and neuromuscular activity during multi-joint isometric exercise

Asymmetry of force generation and neuromuscular activity during multi-joint isometric exercise

Gluteus Medius and Tensor Fascia Latae muscle activation levels during multi-joint strengthening exercises

Abstract Aim: To compare the activation of GMed and TFL in four multi-joint exercises in strength training protocols and to verify if the level of muscle activation is indicated for strength gains in resistance training protocols. Methods: Eleven recreational lifters had normalized muscle activation of GMed and TFL assessed during ten maximal repetitions of four multi-joint exercises: (1) bilateral supine bridge (BiBRG); (2) bilateral supine bridge with hip abducted (BiBRG-AB); (3) unilateral supine bridge (UniBRG) and (4) single-leg squat (SLS). Results: A load of exercises was significantly greater for the BiBRG and BiBRG-AB compared to the UniBRG and SLS (p<0.001). We observed that GMed activation was significant greater compared to TFL among the four exercises (p=0.004) [BiBRG: Δ=26.2%; BiBRG-AB: Δ=27.3%; UniBRG: Δ=24.5% and SLS: Δ=18.8%]. Additionally, GMed activation was classified as moderate (<40%iMVC) and TFL activation was classified as low (<20%iMVC) in all exercises. Conclusion: Our results demonstrated that GMed is more active than TFL in all analyzed exercises. However, the level of activation observed for GMed was below that recommended to strength gain in resistance training programs.

NAO robot for cooperative rehabilitation training.

IntroductionThe aim of this research is to develop a robot-assistive training approach for the disabled individuals with impaired upper limb functions. People with impaired upper limb function can regain their motor functionality undergoing intense rehabilitation exercises. With increasing number of disabled individuals, we face deficiency in the number of expert therapists. One promising remedy could be the use of robotic assistive devices.MethodTo instruct and demonstrate rehabilitation exercise, this research used NAO robot. A library of recommended rehabilitation exercises involving shoulder (i.e., abduction/adduction, vertical flexion/extension, and internal/external rotation), and elbow (i.e., flexion/extension) joint movements was formed in Choregraphe (graphical programming interface). For this purpose, a kinematic model of human upper-extremity was developed based on modified Denavit-Hartenberg notations.ResultIn experiments, NAO robot gave voice instruction and was maneuvered to cooperate and demonstrate the exercises from the library. NAO also plays some complex game with the subject that represents a multi-joint movement's exercise, which was also included in the library.ConclusionsExperimental results with healthy participants reveal that the NAO robot can successfully instruct and demonstrate upper-extremity rehabilitation exercises for single and multi-joint movements. It implies a technical development of cooperative rehabilitation system for which target group will be individuals with upper limb impairment.

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Does the addition of single joint exercises to a resistance training program improve changes in performance and anthropometric measures in untrained men?

The present study compared changes in muscle performance and anthropometric measures in young men performing resistance training (RT) programs composed of only multi joint (MJ) exercises, or with the addition of single joint (SJ) exercises (MJ+SJ). Twenty untrained men were randomized to MJ or MJ+SJ groups for 8 weeks. Both groups performed the same MJ exercises. The difference was that the MJ+SJ group added SJ exercises for upper and lower limbs. Participants were tested for 10 repetitions maximum (10RM), flexed arm circumference, and biceps and triceps skinfolds. Both groups significantly increased 10RM load for the bench press (MJ 38.5%, MJ+SJ 40.1%), elbow extension (MJ 28.7%, MJ+SJ 31.9%), pull down (MJ 34.0% MJ+SJ 38.5%), elbow flexion (MJ 38.2%, MJ+SJ 45.3%), leg press (MJ 40.8%, MJ+SJ 46.8%) and knee extension (MJ 26.9%, MJ+SJ 32.9%), with no significant difference between them. The decreases in biceps (MJ -3.6%, MJ+SJ –3.9%) and triceps (MJ –3.4%, MJ+SJ -3.3%) skinfolds were significant for both groups, with no difference between them. However, the flexed arm circumference increased significantly more for MJ+SJ (5.2%), than for MJ (4.0%). The use of SJ exercises as a complement to a RT program containing MJ exercises brings no additional benefit to untrained men in terms of muscle performance and skinfold reduction, though it promoted higher increases in arm circumference.