Beetroot juice supplementation enhances the effects of blood flow restriction training on lower limb strength and vertical jump performance under fatigue in male university students: a randomized, double-blind, placebo-controlled study.

Combining beetroot juice (BRJ) supplementation with blood flow restriction (BFR) training shows potential to meet the dual demand for enhanced muscle strength and improved fatigue resistance. This study involved 21 male college athletes who were randomized to a BFR group (n = 10) and a BFR-supplemented BRJ group (n = 11, nitrate 8 mmol/day) for 4 weeks of isokinetic BFR training. The strength (at 60°/s, 180°/s, and maximal voluntary isometric contraction) and fatigue resistance of the knee extensors and flexors were assessed pre- and post-intervention using an isokinetic dynamometer and a 30-second anaerobic power test, respectively. The four-week BFR and BFR+BRJ interventions significantly (P < 0.05) improved knee extensor/flexor peak torque and power (at 60°/s and 180°/s), while also delaying the decline in knee extensor torque during the 100-repetition maximal voluntary contraction test. The BFR+BRJ group showed a more significant advantage in the second half of the contraction (51–100 repetitions; P < 0.01). In addition, both interventions significantly reduced the rate of decline in peak torque, peak power, and average power at 60°/s and 180°/s after fatigue, with the reductions being more pronounced in the BFR+BRJ group (P < 0.01). In the anaerobic power test, the BFR+BRJ group maintained a higher power output for a longer duration (P < 0.05) compared to before the intervention, whereas the improvement in the BFR group was limited to the initial 3–10 seconds (P < 0.05). The results suggest that BFR combined with BRJ is an effective training method for improving knee extensor strength performance and fatigue resistance.

Background Multiple sclerosis (MS) affects muscle strength and postural stability. However, the relationship between concentric and isometric strength of knee flexors and extensors and postural stability in mild stage MS is not well known. The aim of the study was to examine the relationship between concentric and isometric strength of knee flexors and extensors and postural stability in mild stage MS patients. Materials and Methods The study included 21 mild-stage MS patients with an EDSS score of 4 or less and 21 healthy controls. The concentric and isometric strength of knee flexors and extensors was measured with the Biodex System 4 Dynamometer, and postural stability with the Biodex Balance System under eyes-open and eyes-closed conditions on a rigid surface. Results Mild-stage MS patients had reduced concentric strength of knee extensors and flexors and increased postural sway compared with healthy controls (p < 0.05). Isometric strength of knee extensors and flexors in mild stage MS patients were similar to healthy controls (p > 0.05). There was a moderate positive correlation between concentric strength of knee extensors and flexors and isometric strength of knee flexors and open-eye postural stability indexes in mild stage multiple sclerosis patients (p < 0.05). Conclusions While isometric strength of knee extensors and flexors was preserved, concentric strength of knee extensors and flexors was decreased, and postural stability was adversely affected in mild stage MS patients. The increase in the strength of the knee muscles was associated with an increase in their postural sway in mild stage MS patients.

Recently, blood flow restriction (BFR) training has gained popularity as an alternative to high-load resistance training for improving muscle strength and hypertrophy. Previous BFR studies have reported positive treatment effects; however, clinical benefits to using BFR following meniscal repair or chondral surgery are unknown. The purpose of this study was to determine the effect of resistance exercises with BFR training versus exercises alone on self-reported knee function, thigh circumference, and knee flexor/extensor strength postmeniscal or cartilage surgery. Single-blinded randomized controlled trial in an outpatient military hospital setting. Twenty participants were randomized into 2 groups: BFR group (n = 11) and control group (n = 9). Participants completed 12weeks of postoperative thigh strengthening. The BFR group performed each exercise with the addition of BFR. Both groups continued with the prescribed exercises without BFR from 12weeks until discharged from therapy. Thigh circumference and self-reported knee function were measured at 1, 6, 12, and 24weeks postoperatively along with knee extensor and flexor strength at 12 and 24weeks. Change scores between time points were calculated for knee function. Limb symmetry indices (LSI) were computed for thigh circumference and knee strength variables. Seventeen participants were included in the final analyses (BFR = 8 and control = 9) due to COVID-19 restrictions. There were no interactions or main effects for group. Time main effects were established for change in knee function scores, thigh circumference LSI, and knee extensor strength LSI. However, knee flexor strength LSI had no main effect for time. The outcomes of this trial suggest that resistance exercises with and without BFR training may result in similar changes to function, thigh atrophy, and knee extensor strength postmeniscus repair/chondral restoration, though further study with larger sample sizes is needed.

Background Inter-limb strength asymmetries are common and can impact functional performance. Blood flow restriction (BFR) training has shown potential to improve strength in the lower limbs, but its effects on reducing asymmetries remain unclear. Aim This study investigated whether a 12-week graded walking program with BFR applied to the weaker lower limb would reduce inter-limb strength asymmetries. Methods A 12-week within-subject, non-randomized intervention study was conducted in healthy asymptomatic adults. Thirty-two participants (20 males, 12 females; 31.1 ± 9.5 years) with inter-limb strength asymmetries ≥ 10% were included. BFR was applied unilaterally to the weaker limb (WL) using a cuff positioned at the gluteal fold and inflated to 90% of each participant’s arterial occlusion pressure (AOP) while the contralateral limb served as the control (CL). Training was performed three times per week (one supervised, two home-based sessions). Isometric knee extensor and flexor strength (assessed using an isokinetic dynamometer) and muscle thickness (assessed by ultrasound) were evaluated before and after the intervention. Results Both limbs showed significant improvements in knee extensor strength ( p &lt; 0.001), with greater gains in the WL (17.5%) vs. CL (6.3%). Knee flexor strength also improved significantly ( p &lt; 0.001) in both limbs, with a small difference between WL (8.7%) and CL (7.4%), suggesting a limited BFR effect. No significant changes in muscle thickness were observed ( p &gt; 0.05). Conclusions A 12-week BFR walking program applied to the weaker limb improved knee extensor strength, particularly in the occluded limb, and reduced inter-limb strength asymmetries. Trial Registration Number Brazilian Registry of Clinical Trials (RBR-5gqgs99), registered November 7th, 2024.

The aim of the present study was to compare the effects of periodic restriction of blood flow to lower extremities with those of isometric exercise on disuse muscular atrophy and weakness induced by immobilization and unloading. The left ankle of each of 15 healthy males was immobilized for 2 wk using cast, and subjects were instructed to walk using crutches with non-weight bearing during this period. Subjects were divided into three groups: a restriction of blood flow (RBF) group (application of external compressive force of 200 mm Hg for 5 min followed by 3 min of rest, repeated five times in a single session, two sessions per day for 14 d); an isometric training (IMT) group (20 "exercises" of 5-s isometric contraction of the knee extensor, flexor, and ankle plantar flexor muscles followed by rest, twice a day, daily for 2 wk); and a control (CON) group (no intervention). We measured changes in muscle strength, thigh/leg circumferences, and serum growth hormone levels. Immobilization/unloading resulted in significant decreases in muscle strength of knee extensor and flexor muscles (P < 0.01 and < 0.05, respectively) and thigh and leg circumferences (P < 0.05, each) in the CON group, and significant decreases in muscle strength of the knee flexor muscles, ankle plantar flexor muscles, and leg circumference (P < 0.05) in the IMT group. RBF protected against these changes in muscle strength and thigh/leg circumference (P < 0.01 and < 0.05, respectively). No changes in serum growth hormone levels were noted. Our results indicate that repetitive restriction of blood flow to the lower extremity prevents disuse muscular weakness.

Although knee extensor muscle strength is strongly associated with postoperative walking ability (PWA) in patients undergoing total knee arthroplasty (TKA), few studies have considered the impact of both knee extensor and flexor muscle strength. This study aimed to determine whether operative side knee flexor and extensor muscle strength before surgery affects the PWA of patients who undergo TKA while accounting for potential covariates. This multicenter retrospective cohort study involved four university hospitals, and patients who underwent unilateral primary TKA were included. The outcome measure was the 5-m maximum walking speed test (MWS), which was completed 12 weeks postoperatively. Muscle strength was measured as the maximum isometric muscle strength required for knee flexor and extensor. Three multiple regression models with a progressively larger number of variables were developed to determine the predictors of 5-m MWS at 12 weeks post-TKA surgery. One hundred thirty-one patients who underwent TKA were enrolled in the study (men, 23.7%; mean age, 73.4 ± 6.9 years). Age, sex, operative side knee flexor muscle strength before surgery, Japanese Orthopaedic Association knee score, and preoperative walking ability were significantly associated with PWA in the final model of the multiple regression analysis ( R2 = 0.35). The current findings suggest that the operative side knee flexor muscle strength before surgery is a robust modifiable predictor of improved PWA. We believe that further validation is needed to determine the causal relationship between preoperative muscle strength and PWA.

Knee muscle atrophy and weakness are common impairments after anterior cruciate ligament (ACL) reconstruction. Blood flow restriction (BFR) training represents a new approach to treat such impairments. However, limited evidence currently exists to support this intervention in related patients. To appraise literature comparing the effects of BFR training with conventional therapy on knee muscle morphological and strength properties in ACL-reconstructed patients. PubMed, SPORTDiscus, CINAHL, and Cochrane Central Register databases were searched for relevant articles from January 1991 through April 2021. Articles were minimum Level 3 evidence focusing on knee muscle morphologic as well as extensor and flexor strength outcomes in ACL-reconstructed patients of all graft types. Systematic review. Level 2. Critical appraisal instruments (Downs and Black checklist, Cochrane Collaboration tool, ROBINS-1 tool) were used to evaluate study quality. We independently calculated effect sizes (ESs) (Cohen d) between groups in each study. The Strength of Recommendation Taxonomy grading scale was used for clinical recommendations. Six articles (4 randomized control studies, 1 nonrandomized study, and 1 case-control study) met inclusion criteria. Exercises paired with BFR training included open kinetic chain, closed kinetic chain, and passive applications. Diverse assessments and time of intervention were observed across studies. ESs ranged from trivial to large in favor of BFR training for muscle morphological (d = 0.06 to 0.81) and strength assessments (d = -0.12 to 1.24) with CIs spanning zero. At this time, grade B or inconsistent and limited-quality patient-oriented evidence exists to support using BFR training to improve or maintain thigh muscle size as well as knee extensor and flexor strength in ACL-reconstructed patients. ESs indicated no consistent clinically meaningful differences when compared with conventional therapy. Subsequent analyses should be repeated as new evidence emerges to update practice guidelines.

To determine whether adjunctive blood flow restriction (BFR) training during postoperative weeks 13-20 is associated with differences in functional, strength, balance, muscle morphology, and neuromuscular outcomes compared with sham BFR following anterior cruciate ligament reconstruction (ACLR). In this single-centre randomized controlled trial, 48 patients aged 18-35 years who underwent primary unilateral ACLR were randomly assigned to a BFR group or a Sham-BFR group. From postoperative weeks 13 to 20, both groups performed identical low-load resistance training (30% one-repetition maximum) twice weekly. The BFR group received individualized blood flow restriction at 40% arterial occlusion pressure, whereas the Sham-BFR group underwent the same protocol with minimal cuff pressure. Outcomes assessed at postoperative week 24 included the International Knee Documentation Committee (IKDC) score, Tegner Activity Scale, knee range of motion (ROM), isometric knee extensor and flexor strength, quadriceps muscle thickness, Y-Balance Test performance, and quadriceps surface electromyography (sEMG). Forty-three patients completed the study (BFR, n = 21; Sham-BFR, n = 22). At 24 weeks postoperatively, the BFR group demonstrated statistically significantly higher IKDC score and Tegner Activity Scale than the Sham-BFR group (p < 0.01). Knee extensor and flexor strength, Y-Balance Test composite scores, and quadriceps sEMG amplitudes were also significantly greater in the BFR group (p < 0.05). No significant between-group differences were observed in knee ROM or quadriceps muscle thickness. Adjunctive BFR training during mid-stage ACLR rehabilitation was associated with more favourable functional, strength, balance, and neuromuscular outcomes than sham BFR at 24 weeks postoperatively. These findings should be interpreted cautiously because baseline outcome measurements and immediate post-intervention assessments were not available. (Chinese Clinical Trial Registry (https://www.chictr.org.cn), No. ChiCTR2400087631, 31/07/2024).

1) To evaluate the effects of a 12-wk high-intensity knee extensor and flexor resistance training program on strength, pain, and adherence in patients with advanced knee osteoarthritis and varus malalignment and 2) to generate pilot data for change in dynamic knee joint load, patent-reported outcomes, and self-efficacy after training. Fourteen patients (48.35 +/- 6.51 yr) with radiographically confirmed medial compartment knee osteoarthritis and varus malalignment of the lower limb were recruited from a surgical waiting list for high tibial osteotomy. Participants completed a high-intensity isokinetic resistance training program three times per week for 12 wk. Knee extensor and flexor strength were assessed every third week, whereas pain and adherence were recorded at every training session. The external knee adduction moment during the gait, the 6-min-walk test, the Knee Injury and Osteoarthritis Outcome Score (KOOS), and the Arthritis Self-Efficacy Scale (ASES) were also evaluated before and after training. Significant improvements in knee extensor and flexor strength were observed without increases in pain during or after training. Adherence to the high-intensity program was high. No significant changes were observed for dynamic knee joint load or the KOOS. There was a significant increase in the function subscale of the ASES only. These findings suggest that patients with advanced knee osteoarthritis and malalignment can experience substantial gains in strength after a high-intensity resistance training program without concomitant increases in pain, adverse events, or compromised adherence. These findings provide support for future clinical trials with longer-term outcomes.

Knee osteoarthritis (OA) is a common condition that limits function and reduces quality of life. Total knee arthroplasty (TKA) is a surgical procedure that replaces the joint surfaces to address anatomical changes due to knee OA. While TKA improves symptoms and function, postoperative impairments are common, including reduced quadriceps strength. Blood flow restriction (BFR) may be a viable option for patients following TKA, as it can improve strength with a minimal amount of joint loading compared to traditional strength training. The purpose of this case report is to describe the impact of BFR use in an individual after TKA, employing pain measurements, quantitative sensory testing, patient-reported outcome measures, physical performance tests, and muscle strength and power testing to explore potential treatment effects and identify potential predictors of response for future studies. A 49-year-old former female triathlete with a history of knee injury and arthroscopic surgery underwent a right TKA and sought physical therapy (PT) due to pain, limited range of motion (ROM), and knee instability during weight bearing activity. PT interventions included manual therapy, gait training, and a home program. Despite participating in supervised PT, she had persistent pain, ROM deficits, and muscle weakness 16 weeks following TKA. BFR was incorporated into her home program, 16-weeks postoperatively. The Short Form McGill Pain Questionnaire-2 (SF-MPQ-2) and Numeric Pain Rating Scale (NPRS) were used to measure pain. Quantitative sensory testing included pressure pain threshold (PPT) and two-point discrimination (TPD) to measure change in sensory perception. Patient-reported outcome measures to assess perceived physical function were the Knee injury and Osteoarthritis Outcome Score (KOOS) and the KOOS- Joint Replacement (KOOS-JR). Physical performance was measured through the 30-second fast walk test (30SFW), timed stair climb test (SCT), 30-second chair standing test (CST), and the timed up and go (TUG). Knee ROM was assessed through standard goniometry. Knee extensor and flexor muscle strength and power were measured with an instrumented dynamometer for isokinetic and isometric testing, generating a limb symmetry index (LSI). Pain and quantitative sensory testing achieved clinically meaningful improvement suggesting reduced sensitivity during and after BFR utilization. Perceived physical function and symptoms significantly improved, particularly in sports and recreation activities, and were best captured in the KOOS, not the KOOS-JR. Physical performance reached clinically meaningful improvement in walking speed, chair stand repetitions, and timed stair climb tests after BFR. Isokinetic and isometric strength and power in knee extensors and flexors increased significantly after BFR compared to the uninvolved leg as determined by LSI. In this case, BFR appeared to be a safe and well-tolerated intervention. The results suggest potential benefits in terms of increased function, strength, power, and reduced pain in this specific person after TKA. Comprehensive pain and sensory assessments alongside clinical measures may help identify suitable patients for BFR after TKA. The KOOS-Sport & Recreation subscale may be more responsive to monitor functional recovery compared to the KOOS-JR, possibly due to the subject's athletic background. 4.

(1) Objective: To examine the effects of blood flow restriction (BFR) training on muscle strength, cross-sectional area and knee-related function in patients selected for anterior cruciate ligament reconstruction (ACLR). (2) Methods: A literature search was conducted in PubMed, PEDro, Cochrane Library, Web of Science, SCOPUS, and ProQuest databases until 20 May 2024. Controlled clinical trials comparing the effects of BFR training with unrestricted training in patients before or after ACLR were selected. The GRADE approach was used to assess the degree of certainty for each meta-analysis. (3) Results: Ten studies were included (n = 287 participants). Standardized mean differences in favor of BFR training applied postoperatively were observed in knee extensor (SMD = 0.79; 95% CI = 0.06 to 1.52; I2: 68%) and flexor isokinetic strength (SMD = 0.53; 95% CI = 0.04 to 1.01; I2: 0%), and quadriceps cross-sectional area (SMD = 0.76; 95% CI = 0.27 to 1.26; I2: 0%). No changes were found in knee extensor isometric strength and knee-related function. The degree of certainty according to the GRADE was very low. (4) Conclusions: Very low degree of certainty suggests that BFR training provides additional benefits to unrestricted training on isokinetic strength and quadriceps cross-sectional area in patients undergoing ACLR.

GH deficiency in adults is associated with reduced muscle mass and muscle strength. The objective of this trial was to follow the effect of 2 yr of GH treatment in GH-deficient adults on muscle performance in relation to a reference population. Knee extensor and flexor strengths for isometric and isokinetic concentric muscle strength were measured using a Kin-Com dynamometer. Hand-grip strength was measured in both hands. The fatigue index was calculated as the percent reduction in peak torque at 50 repeated isokinetic knee extensions. Superimposed, single twitch electrical stimulation was performed. The GH-deficient subjects had lower isometric knee extensor, knee flexor, and hand-grip strength than the reference population. Two years of GH treatment increased and normalized the mean isometric knee extensor and flexor strengths. The concentric knee flexor and extensor strength at an angular velocity of pi rad/s increased, as did the concentric knee flexor strength at an angular velocity of pi/3 rad/s. The increase in muscle strength was more marked in younger patients and in patients with lower initial muscle strength than predicted. Quadriceps endurance decreased, whereas the effect of superimposing single twitches on isometric contraction and hand-grip strength was unaffected by the GH treatment. Two years of GH therapy in GH-deficient adults increased and normalized isokinetic and isometric muscle strength studied in proximal muscle groups. Hand-grip strength and the degree of lack of maximal motor unit activation on voluntary isometric knee extensor force did not change. The dynamic local muscle fatigue index decreased.

Osteoarthritis (OA) knee patients have limited ability in physical function, or difficulties with physical tasks and activities may develop disability. This study aimed to observe the predictors of self-reported and performance-based physical function in patients with knee OA by analyzing the impacts of demographic, pathological, and muscle impairment factors. 135 knee OA patients participated in this study to complete self-reported questionnaires using Knee Injury and Osteoarthritis Outcome Score (KOOS). When measuring performance-based physical function, a 6-meter gait speed (6MGS) test was measured to evaluate their mobility, and a 5-time Sit-to-Stand test (5STS) was assessed to evaluate their balance. Pain intensity, knee extensor and flexor muscle strength, age, body mass index (BMI), durations of symptoms, and radiographic severity were also collected. Spearman correlation and stepwise multiple linear regression were used to explore the association and predictors in self-reported and performance-based physical function. BMI and durations of symptoms did not indicate any significant correlation with either self-reported or performance-based physical function. Age is significantly negatively associated with 6MGS (r 2 = -0.383, p < 0.01), while knee extensor muscle strength has a moderate correlation with 5STS (r 2 = -0.528, p < 0.01). In the stepwise multiple linear regression models, pain intensity (β = 0.712, p < 0.001), knee flexor muscle strength (β = 0.112, p = 0.042) were significantly associated with self-reported physical function in daily activities and contributed to 55.0% of the variance in KOOS-PF score. Knee muscle strength, including knee extensor (5STS: β = -0.428, p < 0.001) and flexor muscle strength (6MGS: β = 0.367, p < 0.001), were the main predictors with performance-based physical function. Pain intensity was the leading risk factor of self-reported physical function, and knee flexor muscle strength contributed as well. The severity of knee OA, durations of symptoms and BMI did not contribute to physical function. However, knee extensor and flexor muscle strength were the main predictors of performance-based performance. Our results show that strengthening of weak knee muscles in both quadriceps and hamstring muscle strength should be considered a priory consideration in knee OA no matter if people are in the early or end-stage of knee OA.

BACKGROUND: Lower-extremity muscle strength and ankle flexibility play key roles in underwater swimming movements. OBJECTIVES: To investigate the relationship between knee isokinetic strength and the speed of underwater dolphin kicks (UDK-S) in competitive male swimmers and identify whether ankle flexibility affects the association between knee isokinetic strength and UDK-S. METHODS: Fifty-two highly trained male swimmers participated in this study. The speed at which the participants travelled 15 m performing UDKs was calculated as UDK-S. Knee flexor and extensor concentric isokinetic strength at fast (240[Formula: see text]/s) and slow (60[Formula: see text]/s) velocities and ankle flexibility were evaluated. Bayesian framework analysis was conducted to examine the relationship between these variables and determine whether this relationship is influenced by ankle flexibility. RESULTS: There was strong-to-extremely strong evidence (Bayes factor [Formula: see text] 24.4 to 198.3) that knee extensor (60[Formula: see text]/s) and knee flexor (60[Formula: see text]/s and 240[Formula: see text]/s) strength are positively and generally moderately correlated with UDK-S. Ankle plantar flexion flexibility was identified to be a moderator between knee extensor strength (60[Formula: see text]/s) and UDK-S. CONCLUSIONS: Knee extensor and knee flexor strength were significantly correlated with UDK-S, and the relationship between knee muscle strength and UDK-S was influenced by ankle plantar flexion flexibility in male competitive swimmers.

Los niveles elevados de fuerza, teóricamente, se relacionan con mejoría en las manifestaciones de la potencia muscular inmediata, que es una variable determinante del rendimiento en el fútbol moderno.OBJETIVO: determinar en futbolistas si el entrenamiento de fuerza en un porcentaje alto (85%) de una repetición máxima (1-RM), buscando el aumento en la fuerza máxima (FM), es más eficaz para mejorar la potencia muscular inmediata que un entrenamiento similar pero al 75% de 1-RM. METODOLOGÍA: sesenta futbolistas de las divisiones inferiores del Deportivo Independiente Medellín fueron divididos aleatoriamente en 2 grupos de 30 jugadores cada uno y se diseñaron los siguientes trabajos de fuerza: el grupo experimental realizó un entrenamiento bilateral e individual de fuerza para los extensores y flexores de la rodilla, consistente en 3 series de 5 repeticiones al 85% de 1-RM, con 5 minutos de descanso entre una y otra serie, 2 veces por semana durante 12 semanas. El grupo control hizo un entrenamiento de fuerza para los mismos músculos, consistente en 3 series de 8 repeticiones al 75% de 1-RM, con 5 minutos de descanso entre una y otra serie, 2 veces por semana durante 12 semanas. Al comienzo del estudio y a las 6 y 12 semanas se hicieron mediciones de fuerza máxima (1-RM) de los extensores y flexores de las rodillas y de la potencia muscular inmediata - velocidad en 20 metros, Squat Jump (SJ) y Countermovement Jump (CMJ). RESULTADOS: aunque los 60 jugadores completaron el entrenamiento de fuerza, sólo se analizaron los datos de 29 del grupo experimental y 27 del grupo control; de los 4 restantes, 2 salieron del equipo y 2 sufrieron lesiones no relacionadas con el entrenamiento. No hubo diferencias significativas entre los dos grupos, en ninguna de las variables ni en ninguna de las 3 mediciones. En la mayoría de las variables - fuerza de los extensores de la rodilla derecha, fuerza de los extensores de la rodilla izquierda, fuerza de los flexores de la rodilla derecha, fuerza de los flexores de la rodilla izquierda, Squat Jump y Countermovement Jump - hubo incrementos estadísticamente significativos (p &lt; 0.05) en cada grupo tanto a las 6 semanas como entre las 6 y las 12 semanas: se exceptuó la velocidad en 20 metros que sólo presentó aumento significativo a las 6 semanas. Para ambos grupos, las correlaciones (r de Pearson) de la fuerza máxima (FM) de los extensores de la rodilla derecha con el SJ y el CMJ fueron de moderadas a fuertes y estadísticamente significativas (p &lt; 0.05) tanto al inicio del estudio como a las 6 y a las 12 semanas de entrenamiento de FM; la correlación con la velocidad en 20 metros se halló sólo al inicio del trabajo. CONCLUSIÓN: el trabajo de FM en intensidades al 75 y 85% de 1-RM produce mejorías significativas en la potencia muscular inmediata.