Leg Press Exercise Research Articles

A BASIC STUDY ON THE EFFECTS OF VIBRATOR-ATTACHED LEG-PRESS ON THE KNEE AND ANKLE JOINT TORQUES

In this study, we compare the effects of vibration on the knee and ankle torques after performing leg-press exercises for four weeks. A total of 20 participants were randomly assigned to a group for leg-press with vibration (VLP group; nine males, one female, 25.8 years old, 172.3[Formula: see text]cm, and 73.8[Formula: see text]kg) and another group for regular leg-press (LP group; eight males, two females, 25.6 years old, 169.6[Formula: see text]cm, and 65[Formula: see text]kg), wherein they performed exercises for four weeks (four times a week). The frequency and amplitude of vibration applied during the exercise were 30[Formula: see text]Hz and 1.5[Formula: see text]mm, respectively. To examine the effects of the exercise, the isometric and isokinetic joint torques of the knee and ankle were measured using Biodex (Biodex Medical Systems, USA) for a total of three times, namely: before exercising and after two and four weeks. The results showed that the isometric and isokinetic joint torques of the knee and ankle improved overall for both groups after four weeks. However, the effects of the leg-press with vibration were not observed. Therefore, further studies are required to investigate the method of applying vibration to each muscle and the frequency and amplitude of vibration, as well as the effects of vibration on the elderly and patients under rehabilitation.

A Novel sEMG Triggered FES-Hybrid Robotic Lower Limb Rehabilitation System for Stroke Patients

Stroke is a leading cause of acquired disability among adults. Current rehabilitation programs result in only partial recovery of motor ability for the patients, which has resulted in an ongoing search for methods to improve the rehabilitation approaches. Therefore, this study presents a novel method for early onset of active rehabilitation by combining an end effector robot with surface electromyography (sEMG) triggered functional electrical stimulation (FES) of rectus femoris and tibialis anterior muscles. This rehabilitation system was demonstrated in 10 able-bodied experimental participants. Defining a successful exercise repetition as a fully completed exercise, from start point to end point followed by a return to start point, when FES onset is triggered by the EMG threshold, the results showed that 97% of the exercise repetitions were successful for a leg press exercise and 100% for a dorsiflexion exercise. Furthermore, an FES stimulation current amplitude of 20–53 mA was required for the leg press exercise and 10–30 mA for the dorsiflexion exercise. The resulting generated force was in the range of 43.0-141.2 [N] for the leg press exercise and 5.4-17.6 [N] for dorsiflexion.

Time-course of changes in performance, biomechanical, physiological and perceptual responses following resistance training sessions

This study determined the time-course of recovery after resistance training (RT) sessions and the association between changes in performance with changes in biomechanical, physiological and perceptual parameters. After a 4-week familiarization period, 14 resistance-trained males performed 3 experimental conditions, each one including 2 sessions with a recovery interval of 24, 48 h or 72 h, in a randomized order. RT sessions consisted of 5 sets of 8-10RM on squat and leg press exercises. The resistance was equal for the 2 sessions of each condition and repetitions were performed until concentric failure. Volume load (VL) and first set volume load (FSVL) were compared between sessions. Tests before each session included countermovement jump (CMJ), maximal voluntary isometric contraction (MVIC), creatine kinase (CK) and delayed onset muscle soreness (DOMS). (2 × 3) ANOVA with effect sizes (ES) assessed the time-course of recovery and Kendall test the correlation between variables (α = 0.05). Significant interaction was observed for all variables, except for CK, where a condition main effect occurred. Comparisons between post and pre-intervals showed VL (p = 0.011;ES = −0.90) decreased for 24 h condition, while FSVL remained decreased for 48 h (p = 0.031;ES = −0.63) and DOMS increased (p = 0.001;ES = 3.52). CMJ (p = 0.025;ES = 0.25) and MVIC (p = 0.031;ES = 0.14) performance increased at 72 h. FSVL (r = 0.424), CMJ (r = 0.439), MVIC (r = 0.389) and DOMS (r = −0.327) were significantly correlated with VL (p < 0.05). Time-course of VL showed the necessity of at least 48 h for the reestablishment of performance, though better perceptual responses were evident at 72h. Thus, both recovery intervals may be beneficial after lower-limbs RT until concentric failure, though chronic effects still need to be investigated.

CONCURRENT VALIDITY OF INSTRUMENTS FOR MEASURING SPEED OF MOVEMENT IN LEG PRESS EXERCISES

ABSTRACT Introduction Adequate measurement of movement velocity in strength exercises can assist in the prescription and evaluation of training effects. Objective The objectives of the present study were to analyze the reliability (test-retest) and concurrent validity of the movement velocity measured by means of the electrogoniometer and accelerometer during horizontal leg press exercise at different intensities (40, 60, 80% of a maximum repetition - 1RM). Methods Eighteen young women attended the laboratory on five occasions. After determining the maximum dynamic force, two visits (separated by 48-72 hours) were used to verify the reliability (test-retest) for different speed variables in the three intensities. Results The mean propulsive velocity obtained by the goniometer showed higher Intraclass correlation coefficients (ICC) and lower coefficients of variation compared to the accelerometer. The same behavior was observed for both the mean velocity and the peak velocity. The propulsive time was more reproducible and with less variation for the accelerometer and bad CCI for both sensors were observed at 60% of 1RM. When the sensors are compared, the mean and average propulsive velocities presented moderate ratios with a large to very large standardized medium bias. Conclusion The potentiometer of the electrogoniometer can be used to estimate the velocity in the horizontal leg press exercise, especially for loads of 60 and 80%. The performance of the accelerometer was inferior to that of the potentiometer. Level of evidence II; Diagnostic studies.

Movement Velocity as A Measure of Exercise Intensity in Persons with Multiple Sclerosis: A Validity Study.

Objectives: This study aims to analyse the validity (agreement between two methods) of the movement propulsive velocity (MPV) as an indicator of relative load in leg press (LP) and bench press (BP) exercises in persons with multiple sclerosis (MS). Methods: 18 persons with MS (sex = 55% male; age (mean ± SD) = 44.88 ± 10.62 years; body mass = 67.19 ± 10.63 kg; height = 1.66 ± 0.07 m; Expanded Disability Status Scale (EDSS) = 3.12 ± 1.73) performed an incremental loading test in BP and LP exercises in two separate sessions. Individual determination of the one-repetition maximum (1RM) and full load-velocity profile were obtained for each participant. Results: a significant linear relationship was observed between the %1RM load and the MPV in LP (%1RM = −133.58 × MPV + 117.44; r2 = 0.84; standard error of the estimate (SEE) = 9.38%1RM) and BP (%1RM = −95.66 × MPV + 115.26; r2 = 0.86; SEE = 9.82%1RM). In addition, no significant differences were found between the %1RM achieved directly and the %1RM obtained by the equation calculated from the linear regression (LP, p = 0.996; BP, p = 0.749). Conclusions: these results indicate that movement velocity can estimate the relative load in bench press and leg press exercises in persons MS.

Enhanced Blood Supply Through Lower Body Negative Pressure During Slow-Paced, High Load Leg Press Exercise Alters the Response of Muscle AMPK and Circulating Angiogenic Factors

Lower body negative pressure (LBNP) is an established method of simulating the gravitational effects of orthostasis on the cardiovascular system during space flight or at supine body position on Earth. We hypothesized that LBNP added onto leg press exercise would promote leg muscle perfusion, stimulate oxygen consumption, and modify acute molecular responses. Eighteen subjects performed fifteen slow-paced concentric (4 s) and eccentric contractions (4 s) without or with 40 mmHg LBNP. Force corresponding to 6% of the one-repetition maximum (1-RM) at knee flexion gradually increased to 60% 1-RM within the first half of the range of motion, thereafter remaining constant. AMPK and P-AMPK protein expression was determined in biopsies of vastus lateralis. Venous blood samples were used to measure angiogenic factors. Physiological responses to LBNP included an elevated EMG amplitude, higher heart rate and doubling of the cardiac output compared to control (p < 0.001). Muscle total hemoglobin was increased by around 20 μmol/l vs. control (p < 0.001), accompanied by decreasing tissue oxygen saturation and elevated oxygen uptake (p < 0.05). MMP-2 levels were reduced, and the ratio of P-AMPK to AMPK elevated after exercise with LBNP (p < 0.05). MMP-9 similarly increased in both groups, whereas endostatin was only elevated in the control group (p < 0.05). Our results indicate facilitated peripheral blood supply and higher oxygen exploitation leading to activation of the energy sensor AMPK and differential regulation of angiogenic factors involved in muscle tissue remodeling and capillary growth. Simulating orthostasis with LBNP might promote beneficial structural adaptations of skeletal muscles during resistance exercise and contribute to future exercise countermeasures achieving increased muscle strength and endurance during space flight.

Four weeks of augmented eccentric loading using a novel leg press device improved leg strength in well-trained athletes and professional sprint track cyclists.

This study assessed the efficacy of strength training using augmented eccentric loading to provoke increases in leg strength in well-trained athletes, and sprint track cyclists, using a novel leg press device. Twelve well-trained athletes were randomly allocated traditional resistance training (TRAD, n = 6), or resistance training using augmented eccentric loading (AEL, n = 6). A further 5 full-time, professional sprint track cyclists from a senior national squad programme also trained with augmented eccentric loading (AEL-ATH) alongside their usual sport-specific training. Participants completed four weeks of twice-weekly resistance training using the leg press exercise. In TRAD the lowering phase of the lift was set relative to concentric strength. In AEL and AEL-ATH the lowering phase was individualised to eccentric strength. Concentric, eccentric, isometric and coupled eccentric-concentric leg press strength, and back squat 1 repetition maximum (1RM), were assessed pre- and post-training. The AEL and AEL-ATH groups performed the eccentric phase with an average 26 ± 4% greater load across the programme. All groups experienced increases in concentric (5%, 7% and 3% for TRAD, AEL & AEL-ATH respectively), eccentric (7%, 11% and 6% for TRAD, AEL & AEL-ATH respectively), and squat 1RM (all p < 0.05), where the AEL-ATH group experienced relatively greater increases (13% vs. 5% in TRAD and AEL, p < 0.01). The TRAD and AEL groups also increased isometric strength (p < 0.05). A four-week period of augmented eccentric loading increased leg strength in well-trained athletes and track cyclists. The eccentric leg press stimulus was well-tolerated, supporting the inclusion of such training in the preparation programmes of athletes.

Does Muscle Hypertrophy Relate To Resistance Training-Induced Changes In Myofibrillar Protein Synthesis In Women?

Resistance exercise (RE) elevates skeletal muscle myofibrillar protein synthesis (MyoPS) for up to 48h, which can be measured under ‘free-living’ conditions using deuterium oxide (D2O). The accumulation of repeated bouts of RE (resistance training—RT) results in skeletal muscle hypertrophy, which in men has been reported to correlate with post-RE ‘free-living’ MyoPS only in the trained state. However, the impact of training status on acute responses to RE and their relationship to hypertrophic adaptations has yet to be investigated in women. PURPOSE: The present study examined the MyoPS response over 48h of recovery from an acute bout of RE in the untrained (UT) and trained (T) state to determine its association with hypertrophic adaptations in women. METHODS: Ten recreationally active young women (23±5 yr, 62.3±12.0 kg, 23.7±7.4 % body fat; mean±SD) underwent ~8 wk of supervised whole-body RT (4 x 10 repetitions, 75% 1 repetition maximum (1RM), 3x/wk). Whole-body fat free mass (FFM; BODPOD), vastus lateralis muscle thickness (MT; B-mode ultrasound) and 1RM for each completed exercise were measured in the UT and T state to quantify training responses. MyoPS was measured during the mid-follicular phase (day 3-9 of the menstrual cycle) at rest pre-training and for 48h following the first and final bout of RE using orally administered D2O. Muscle biopsies were obtained at pre-RE (0h), 24h and 48h post-RE to determine MyoPS in both the UT and T state. RESULTS: Following RT, there was a ~3.4% increase in FFM (49.3±6.4 vs. 51.0±6.9 kg; P < 0.001) and ~8.8% increase in MT (2.31±0.39 vs. 2.50±0.38 cm; P < 0.05). Representative 1RM strength increased for bench press and leg press exercise (28.5±5.8 kg vs. 38.7±9.8 kg and 151.6±63.5 vs. 259.3±92.7 kg, respectively; P < 0.01). Forthcoming analysis will determine if: i) training alters the post-exercise MyoPS response, and; ii) whether muscle hypertrophy correlates with acute MyoPS in the UT and/or T state. CONCLUSIONS: Women responded favourably to ~8 wk of RT with significant gains in FFM, MT and 1RM strength. Ongoing analysis will provide insight into the potential relationship between acute muscle protein synthesis and training-induced hypertrophy in the understudied female population. Supported by the Natural Sciences and Engineering Research Council of Canada.

Changes In Muscle Power After Usual Care Or Early Structured Exercise Intervention In Acutely Hospitalized Older Adults: A Secondary Analysis Of A Randomized Controlled Trial.

PURPOSE: To assess the effects of a multicomponent exercise training intervention on dynamic and isometric maximal muscle strength of lower and upper extremities and muscle power output in acutely hospitalized older adults. METHODS: A secondary analysis of a single-blind randomized clinical trial in an acute care for elderly (ACE) unit in a tertiary public hospital in Navarre (Spain). 370 hospitalized patients (aged ≥75 years) were randomly allocated to an exercise intervention (n=185) or a usual care (n=185) group. The intervention consisted of a multicomponent exercise-training program performed during 5-7 consecutive days (2 sessions/day). The usual care group received habitual hospital care, which included physical rehabilitation when needed. The main endpoints were change in maximal dynamic strength (i.e., leg-press, chest-press, and knee extension exercises) and maximal isometric knee extensors and hip flexors strength from baseline to discharge. Changes in muscle power output at submaximal and maximal loads were also measured after the intervention period. RESULTS: The physical exercise program provided significant benefits over usual care. At discharge, the exercise group showed a mean increase of 19.6 kg (95% confidence interval [CI], 16.0, 23.2; p<0.001) on the one-repetition maximum (1RM) in the leg-press exercise, 5.7 kg (95%CI, 4.7, 6.8; p<0.001) on the 1RM in the chest-press exercise, and 9.4 kg (95%CI, 7.3, 11.5; p<0.001) on the 1RM in the knee extension exercise over usual-care group. There were improvements in the intervention group also in the isometric maximal knee extension strength (14.8 Newtons (N); 95%CI, 11.2, 18.5 vs. -7.8 N; 95%CI, -11.0, -3.5 in the control group; p<0.001) and the hip flexion strength (13.6 N; 95%CI, 10.7, 16.5 vs. -7.2 N; 95%CI, -10.1, -4.3; p<0.001). Significant benefits were also observed in the exercise group for the muscle power output at submaximal loads (i.e., 30%1RM, 45%1RM, 60%1RM, and 75%1RM; all p<0.001) over usual care group. CONCLUSIONS: An individualized, multicomponent exercise-training program, with special emphasis on muscle power training, proved to be an effective therapy for improving muscle power output of lower limbs at submaximal loads and maximal muscle strength in very old patients during acute hospitalization.

The Effects Of A Protease Enzyme Blend On The Amino Acid Response To Resistance Exercise

PURPOSE: The aim of the current study was to examine the efficacy of whey protein ingestion with or without a protease enzyme complex on amino acid (AA) availability following acute lower-body resistance exercise. METHODS: Ten resistance trained men (24.4±4.1yr, 179.1±8.6cm, 92.6±10.4kg) with at least one year of resistance training experience volunteered to participate in this placebo-controlled, randomized, cross-over designed study. Following an overnight fast, participants performed lower-body acute resistance exercises consisting of four sets each of the leg press and leg extension exercises (8-10 repetitions at 75% of 1RM) followed by consumption of one of three drinks of equivalent volume, taste, and appearance which consisted of either: (a) 26g whey protein + 250 mg protease supplement + whey (PW) (b) 26g whey protein (W), or (c) a non-caloric flavored water drink (PL). Blood samples were collected before exercise, immediately-post (0min), 30-, 60-, 90-, 120-, and 180-minutes post-exercise (30min, 60min, 90min, 120min, 180min respectively). Plasma amino acid samples were analyzed for essential (EAA), branched-chained (BCAA), and leucine concentrations via liquid chromatography-mass spectrometry (LC-MS). A 2-way repeated measures analysis of variance (ANOVA) was used to identify differences between treatments over time. Area under the curve was calculated via the trapezoidal technique and analyzed via a one-way ANOVA. RESULTS: Significant main effects for time (p<0.001) and time x group interactions (p<0.001) were found for leucine, BCAA, and EAA. PW drink resulted in significantly greater plasma leucine, BCAA and EAA concentrations at 30 min compared to PL (p<0.001) while not different than W. Leucine was significantly elevated at 30min (p=0.007) and EAAs at 180min (p=0.004) compared to 0min for PW. The AUC for PW and W were both significantly elevated for leucine, BCAAs and EAAs compared to PL (p<0.001). CONCLUSION: While no significant differences were found between the W and PW supplementation groups during the 3-hr period after resistance training; the PW group produced significantly greater leucine concentrations at 30min and for EAAs at 180min than PL compared to 0min. Results indicate that PW may provide a modest improvement of AA appearance in blood following acute resistance exercise.

Flow-Mediated Dilation in Healthy Young Individuals Is Impaired after a Single Resistance Exercise Session.

The current pool of data investigating the effects of a single resistance exercise session on endothelial function is divergent and inconclusive. Therefore, the purpose of the present study was to evaluate the effect of a single resistance exercise session on flow-mediated dilation (FMD) in trained individuals. Eleven healthy, young, recreationally resistance-trained individuals participated in the study. After determining the resistance exercise workload, the participants performed three sets of 10–12 repetition of leg press and leg extension exercises. By using ultrasound equipment, brachial artery FMD was assessed before (PRE) and 30 min after (POST) the resistance exercise protocol or resting (control) to evaluate endothelial function. A significant reduction in FMD response (PRE: 5.73% ± 1.21% vs. POST: 4.03% ± 1.94%, p < 0.01) after resistance exercise was observed, accompanied by a large effect size (d = 1.05). No significant difference was observed in FMD in the control condition (PRE: 5.82% ± 1.19% vs. POST: 5.66% ± 1.24%, p = 0.704). Additionally, no significant difference in baseline brachial artery diameter between resistance exercise (PRE: 3.30 ± 0.32 vs. POST: 3.40 ± 0.34 mm, p = 0.494) and resting (PRE: 3.64 ± 0.41 vs. POST: 3.67 ± 0.62 mm, p = 0.825) was observed. Our findings showed that a single resistance exercise session induced a reduction in FMD in resistance-trained individuals.

Evaluation of the Lower Limb Muscles' Electromyographic Activity during the Leg Press Exercise and Its Variants: A Systematic Review.

The aim of this study was to analyze the literature on muscle activation measured by surface electromyography (sEMG) of the muscles recruited when performing the leg press exercise and its variants. The Preferred Reporting Items of Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed to report this review. The search was carried out using the PubMed, Scopus, and Web of Science electronic databases. The articles selected met the following inclusion criteria: (a) a cross-sectional or longitudinal study design; (b) neuromuscular activation assessed during the leg press exercise, or its variants; (c) muscle activation data collected using sEMG; and (d) study samples comprising healthy and trained participants. The main findings indicate that the leg press exercise elicited the greatest sEMG activity from the quadriceps muscle complex, which was shown to be greater as the knee flexion angle increased. In conclusion, (1) the vastus lateralis and vastus medialis elicited the greatest muscle activation during the leg press exercise, followed closely by the rectus femoris; (2) the biceps femoris and the gastrocnemius medialis showed greater muscular activity as the knee reached full extension, whereas the vastus lateralis and medialis, the rectus femoris, and the tibialis anterior showed a decreasing muscular activity pattern as the knee reached full extension; (3) evidence on the influence of kinematics modifications over sEMG during leg press variants is still not compelling as very few studies match their findings.

Resistance Exercise and Knee Osteoarthritis

Resistance Exercise and Knee Osteoarthritis

INDICATORS OF NEUROMUSCULAR FATIGUE IN LEG PRESS EXERCISE IN MEN AND WOMEN

ABSTRACT Introduction Muscle fatigue is characterized by reduced ability to produce maximum strength or power, and may differ between men and women. Changes in velocity of movement during exercise, and in the ability to produce strength after exercise, may help when comparing fatigue in men and women. Objective To analyze the differences between men and women in relation to number of repetitions, kinetics, kinematics and isometric force-time curve performance, and their respective muscle activation in horizontal leg press exercises. Methods Fifteen men and fifteen women underwent isometric force-time curve (Cf-t) and electromyographic (EMG) assessments before and after performing horizontal leg press exercises. The exercises were performed in three sets until voluntary exhaustion, at 70% maximal repetition. During the exercises, kinetic and kinematic variables were obtained by means of two force transducers, a linear position potentiometer and accelerometer adapted for the horizontal leg press and synchronized by a signal conditioning plate. Results The mean propulsive velocity significantly reduced between the first and last repetition of each series, with a similar reduction for men (-12.4 to -29.2%) and women (-29.2 to -35.6%). The same pattern was observed for the other kinetic and kinematic variables. The maximum voluntary contraction and peak force development rate also decreased for both men (-15.1 ± 8.7% and -26.9 ± 21.2%, respectively) and women (-13.9 ± 10.4% and -28.2 ± 11.5%, respectively). Conclusion Based on the different variables used to quantify the effect of fatigue during and after horizontal leg press exercises, the research found practically no differences between men and women. Level of evidence II; Comparative prospective study.

Muscle activation during leg-press exercise with or without eccentric overload.

This study sought to investigate the electromyographic activity of the vastus lateralis (VL) muscle during concentric-eccentric exercise using a new concept leg press machine enabling a preset overloading in the eccentric phase. Ten young males familiar with resistive exercise were recruited for this study. Tests were performed on a Leg-press Biostrength® (Technogym S.p.A., Italy). The load was set to 70% and 80% of one-repetition maximum (1-RM). The participants performed 2 sets of 6 repetitions at each relative load with (ECC +) and without (ISOW) an eccentric overload equivalent to 150% of the concentric load. A metronome was employed to maintain the selected cadence. Sets were separated by a 5-min rest. Surface electromyography (EMG) of VL was recorded and integrated (iEMG). Results showed a higher iEMG in ECC + with respect to ISOW at both intensities (+ 29% for 70% 1-RM, p < 0.01 and + 31% for 80% 1-RM, p < 0.001). No statistically significant differences were detected between concentric and eccentric phase in both ECC + conditions. Training with a 150% eccentric overload provides a ~ 30% greater motor unit recruitment of the VL muscle in leg press exercise. Moreover, the results show that the eccentric overloading provided by the Biostrength® machine enables training at the same level of neural activation of the concentric phase. Hence, the derecruitment of motor units, normally observed during the eccentric phase when using conventional training machines, was overcome using the Biostrength® machine; this observation seems particularly important for maximizing neuromuscular responses to strength training.

Comparison of linear, hyperbolic and double-hyperbolic models to assess the force–velocity relationship in multi-joint exercises

This study assessed the validity of linear, hyperbolic and double-hyperbolic models to fit measured force–velocity (F–V) data in multi-joint exercises and the influence of muscle excitation on the F–V relationship. The force–joint angle and F–V relationships were assessed in 10 cross-training athletes and 14 recreationally resistance-trained subjects in the unilateral leg press (LP) and bilateral bench press (BP) exercises, respectively. A force plate and a linear encoder were installed to register external force and velocity, respectively. Muscle excitation was assessed by surface EMG recording of the quadriceps femoris, biceps femoris and gluteus maximus muscles during the unilateral LP. Linear, Hill’s (hyperbolic) and Edman’s (double-hyperbolic) equations were fitted to the measured F–V data and compared. Measured F–V data were best fitted by double-hyperbolic models in both exercises (p < 0.05). F–V data deviated from the rectangular hyperbola above a breakpoint located at 90% of measured isometric force (F 0) and from the linearity at ≤45% of F 0 (both p < 0.05). Hyperbolic equations overestimated F 0 values by 13 ± 11% and 6 ± 6% in the LP and BP, respectively (p < 0.05). No differences were found between muscle excitation levels below and above the breakpoint (p > 0.05). Large associations between variables obtained from linear and double-hyperbolic models were noted for F 0, maximum muscle power, and velocity between 25% and 100% of F 0 (r = 0.70–0.99; all p < 0.05). The F–V relationship in multi-joint exercises was double-hyperbolic, which was unrelated with lower muscle excitation levels. However, linear models may be valid to assess F 0, maximal muscle power and velocity between 25% and 100% of F 0.

Acute Physiological Responses to Resistance Exercise With Continuous Versus Intermittent Blood Flow Restriction: A Randomized Controlled Trial.

The primary goal of this investigation was to examine the physiological responses of blood flow restriction (BFR) resistance exercise (RE) performed with continuous or intermittent BFR and to compare these results to those from conventional high- and low-load RE without BFR. Fourteen men randomly completed the following experimental trials: (1) low-load RE with continuous BFR (cBFR), (2) low-load RE with intermittent BFR (iBFR), (3) low-load RE without BFR (LI), and (4) conventional high-load RE without BFR (HI). For the cBFR, iBFR, and LI exercise trials, participants performed four sets of 30–15–15–15 repetitions of the bilateral leg press (LP) and knee extension (KE) exercises, at an intensity of 20% of their one-repetition maximum (1-RM), at a 1.5-s contraction speed, and with a 1-min rest period between sets. The only difference between the cBFR and iBFR protocols was that the pressure of the cuffs was released during the rest intervals between sets for the iBFR trial. For the HI trial, participants completed four sets of 10 repetitions of the same exercises, at 70% of 1-RM, with a 1-min rest period between sets, and at the same contraction speed. Muscle activity was assessed during each set using superficial electromyography, as well as changes in blood lactate concentration [La–] from baseline at 5 min post exercise and in muscle swelling and plasma volume (%ΔPV) at 5 and 15 min post exercise. There were no significant differences in muscle activity (p < 0.05) across the cBFR, iBFR, and LI protocols at any time point, whereas they were all significantly lower than HI. There were also no significant (p < 0.05) differences across the three low-load RE conditions for [La–],%ΔPV, or muscle swelling. HI elicited significantly (p < 0.05) greater responses than cBFR, iBFR, and LI for all the physiological markers measured. In conclusion, RE combined with cBFR or iBFR induce the same acute physiological responses. However, the largest physiological responses are observed with HI, probably because of the significantly greater exercise volumes. Therefore, releasing the pressure of the restrictive cuffs during the rest periods between sets will not hinder the acute physiological responses from BFR RE.

Changes in muscle power after usual care or early structured exercise intervention in acutely hospitalized older adults

BackgroundA classic consequence of short‐term bed rest in older adults is the significant loss in skeletal muscle mass and muscle strength that underlies the accelerated physical performance deficits. Structured exercise programmes applied during acute hospitalization can prevent muscle function deterioration.MethodsA single‐blind randomized clinical trial conducted in an acute care for elders unit in a tertiary public hospital in Navarre (Spain). Three hundred seventy hospitalized patients [56.5% female patients; mean age (standard deviation) 87.3 (4.9) years] were randomly allocated to an exercise intervention (n = 185) or a control (n = 185) group (usual care). The intervention consisted of a multicomponent exercise training programme performed during 5–7 consecutive days (2 sessions/day). The usual‐care group received habitual hospital care, which included physical rehabilitation when needed. The main endpoints were change in maximal dynamic strength (i.e. leg‐press, chest‐press, and knee extension exercises) and maximal isometric knee extensors and hip flexors strength from baseline to discharge. Changes in muscle power output at submaximal and maximal loads were also measured after the intervention.ResultsThe physical exercise programme provided significant benefits over usual care. At discharge, the exercise group showed a mean increase of 19.6 kg [95% confidence interval (CI), 16.0, 23.2; P < 0.001] on the one‐repetition maximum (1RM) in the leg‐press exercise, 5.7 kg (95% CI, 4.7, 6.8; P < 0.001) on the 1RM in the chest‐press exercise, and 9.4 kg (95% CI, 7.3, 11.5; P < 0.001) on the 1RM in the knee extension exercise over usual‐care group. There were improvements in the intervention group also in the isometric maximal knee extension strength [14.8 Newtons (N); 95% CI, 11.2, 18.5 vs. −7.8 N; 95% CI, −11.0, −3.5 in the control group; P < 0.001] and the hip flexion strength (13.6 N; 95% CI, 10.7, 16.5 vs. −7.2 N; 95% CI, −10.1, −4.3; P < 0.001). Significant benefits were also observed in the exercise group for the muscle power output at submaximal loads (i.e. 30% 1RM, 45% 1RM, 60% 1RM, and 75% 1RM; all P < 0.001) over usual‐care group.ConclusionsAn individualized, multicomponent exercise training programme, with special emphasis on muscle power training, proved to be an effective therapy for improving muscle power output of lower limbs at submaximal loads and maximal muscle strength in older patients during acute hospitalization.

Blood Flow Restriction Training Applied With High-Intensity Exercise Does Not Improve Quadriceps Muscle Function After Anterior Cruciate Ligament Reconstruction: A Randomized Controlled Trial

Background: A major goal of rehabilitation after anterior cruciate ligament reconstruction (ACLR) is restoring quadriceps muscle strength. Unfortunately, current rehabilitation paradigms fall short of this goal, such that substantial quadriceps muscle strength deficits can limit return to play and increase the risk of recurrent injuries. Blood flow restriction training (BFRT) involves the obstruction of venous return to working muscles during exercise and may lead to better recovery of quadriceps muscle strength after ACLR. Purpose: To examine the efficacy of BFRT with high-intensity exercise on the recovery of quadriceps muscle function in patients undergoing ACLR. Study Design: Randomized controlled trial; Level of evidence, 2. Methods: A total of 34 patients (19 female, 15 male; mean age, 16.5 ± 2.7 years; mean height, 169.0 ± 19.7 cm; mean weight, 73.2 ± 17.7 kg) scheduled to undergo ACLR were randomly assigned to 1 of 4 groups: concentric (n = 8), eccentric (n = 8), concentric with BFRT (n = 9), and eccentric with BFRT (n = 9). The exercise component of the intervention consisted of patients performing a single-leg isokinetic leg press, at an intensity of 70% of the patients’ 1-repetition maximum during either the concentric or eccentric action, for 4 sets of 10 repetitions 2 times per week for 8 weeks beginning at 10 weeks postoperatively. Patients randomized to the BFRT groups performed the leg-press exercise with a cuff applied to the thigh, set to a limb occlusion pressure of 80%. Isometric and isokinetic (60 deg/s) quadriceps peak torque, quadriceps muscle activation, and rectus femoris muscle volume were assessed before ACLR, after BFRT, and at the time that patients returned to activity and were converted to the change in values from baseline for analysis. Also, 1-way analyses of covariance were used to compare the change in values for each dependent variable between groups after BFRT and at return to activity (P ≤ .05). Results: No significant differences were found between groups for any outcome measures at either time point (P > .05). Conclusion: An 8-week BFRT plus high-intensity exercise intervention did not significantly improve quadriceps muscle strength, activation, or volume. On the basis of our findings, the use of BFRT in conjunction with high-intensity resistance exercise in patients undergoing ACLR to improve quadriceps muscle function may not be warranted. Registration: NCT03141801 (ClinicalTrials.gov identifier)

The effect of blood flow restriction exercise on exercise-induced hypoalgesia and endogenous opioid and endocannabinoid mechanisms of pain modulation.

This study aimed to investigate and compare the magnitude of exercise-induced hypoalgesia (EIH) with low-intensity blood flow restriction (BFR) resistance exercise (RE) at varying pressures to other intensities of resistance exercise and examine endogenous mechanisms of pain reduction. Twelve individuals performed four experimental trials involving unilateral leg press exercise in a randomized crossover design: low-load RE at 30% of one repetition maximum (1RM), high-load RE (70% 1RM), and BFR-RE (30% 1RM) at a low and high pressure. BFR pressure was prescribed relative to limb occlusion pressure at 40% and 80% for the low- and high-pressure trials. Pressure pain thresholds (PPT) were assessed before and 5 min and 24 h following exercise in exercising and nonexercising muscles. Venous blood samples were collected at the same timepoints to determine plasma concentrations of beta-endorphin and 2-arachidonoylglycerol. High-pressure BFR-RE increased PPTs in the exercising limb to a greater extent than all other trials. Comparable systemic EIH effects were observed with HLRE and both BFR-RE trials. PPTs in the exercising limb remained elevated above baseline at 24 h postexercise following both BFR-RE trials. Postexercise plasma beta-endorphin concentration was elevated during the BFR-RE trials. No changes to 2-arachidonoylglycerol concentration were observed. High pressure BFR-RE causes a greater EIH response in the exercising limb that persists for up to 24 h following exercise. The reduction in pain sensitivity with BFR-RE is partly driven by endogenous opioid production of beta-endorphin. BFR-RE should be investigated as a possible pain-modulation tool in individuals with acute and chronic pain.NEW & NOTEWORTHY High-pressure blood flow restriction (BFR) causes a greater hypoalgesia response in the exercising limb (48%) compared with light and heavy load resistance exercise (10-34%). Performing light load resistance exercise with BFR causes systemic hypoalgesia comparable with heavy load resistance exercise (10-18%). BFR resistance exercise prolonged the exercise-induced hypoalgesia response for 24 h in the exercising limb (15% and 24%, respectively). Activation of endogenous opioid production and a conditioned pain modulation effect partly mediate the relationship between exercise and hypoalgesia.