High-load Resistance Exercise Research Articles

Mood Effects of Blood Flow Restriction Resistance Exercise Among Basketball Players.

This study compared the acute effects of resistance exercise with and without blood flow restriction (BFR) on basketball players' mood states. A total of 11 male basketball players (M age = 19.9, SD = 2.8 years; M height = 180.8, SD = 7.8 cm; M weight = 71.1, SD = 9.1 kg; M body mass index = 22.1, SD = 1.9 kg/m2) were randomly assigned to two experimental conditions: (a) low-load resistance exercise with BFR (LLRE + BFR) and high-load resistance exercise (HLRE) without BFR. We measured mood state with the Brunel Mood Scale before and after each session. There was a significant interaction effect such that there was increased fatigue over time with LLRE + BFR ( p = .001, Δ% = 169.2). Regarding total mood disorder, there were significant pre and postexercise differences between athletes exposed to both the LLRE + BFR and HLRE conditions ( p = .048) and a decharacterization of the iceberg mood profile in the post-training LLRE + BFR condition. LLRE + BFR, compared to HLRE, promoted an acute negative effect on mood state, decharacterization of the iceberg profile, total mood disturbance, and increased participant fatigue, suggesting that this method of strength training should be avoided before sports competitions.

Cardiovascular Responses to Blood Flow Restriction and Very Low Load Resistance Exercise in the Upper Body

Blood flow restriction (BFR) applied as a percentage of arterial occlusion pressure (AOP) combined with low load resistance exercise in the upper body elicits a cardiovascular response that, compared to high-load resistance exercise, appears dependent upon the load as well as the cuff pressure. The response to very low load resistance exercise (15% 1RM) combined with BFR is unknown. PURPOSE: To investigate the cardiovascular and hemodynamic responses to very low load resistance exercise combined with BFR, and compare these to high load resistance exercise in the upper body. METHODS: Sixty-six (50% men) participants (18-35 yrs) were recruited and, following 1RM testing, were randomly assigned to either high load (HL) at 70% 1RM or very low load at 15% 1RM. Very low-load conditions were no restriction (VLL0), 40% AOP (VLL40), or 80% AOP (VLL80) applied using a 5cm cuff. Four sets of unilateral biceps curls were performed to failure or 90 repetitions, whichever occurred first. Blood pressure (SBP/DBP) was taken before and after. Ultrasound measures of blood flow (BF) were taken at rest, following Set 2, and 1 minute after exercise. Repeated measures ANOVA tests were performed to determine whether differences occurred across time and condition. Results presented as mean (SD). RESULTS: Participants were 1.72 (0.1) m tall, weighed 72.0 (13.8) kg, with a 1RM of 15.9 (7.4) kg, and AOP of 103 (73) mmHg. There were no interactions for SBP (p = 0.416), DBP (p = 0.414), but an interaction existed for BF (p < 0.0005). Main effects of time found that SBP [change of 10 (10) mmHg] and DBP [change of 6 (13) mmHg] increased. BF increased following Set 2 in all conditions except for VLL80 (p=0.129), which remained similar to pre until 1 minute post deflation [change of 378 (256) ml·min-1]. Following set 2, BF was similar between VLL0 [547 (244) ml·min-1] and HL [465 (269) ml·min-1]; both were greater than VLL40 [365 (189) ml·min-1] and VLL80 [128 (75) ml·min-1]. At 1 minute post, there were no differences in BF between VLL0: 438 (227), VLL40: 470 (248), VLL80: 464 (290), and HL: 364 (239) ml·min-1. CONCLUSIONS: The hemodynamic response to very low load resistance exercise combined with BFR at different pressures is similar to high load resistance exercise when performed in the upper body, although the BF response differs per the cuff pressure.

Acute effects of blood flow restriction on exercise-induced free radical production in young and healthy subjects

The main purpose of this study was to investigate the acute local and systemic effects of low-load resistance exercise (30% 1RM) with partial vascular occlusion on exercise-induced free radical production and to compare these effects with other established training methods.Fifteen young and healthy males (25 ± 3 years) performed the following four sessions in a counterbalanced order on separate days: low-load resistance exercise (LI: 30% 1RM), low-load resistance exercise with blood flow restriction (LIBR: 30% 1RM), high-load resistance exercise (HI: 80% 1RM) and an additional session without exercise but blood flow restriction only (BR). Blood samples were obtained 15 min prior to and immediately after exercise sessions from the right index finger and first toe. To analyze concentrations of reactive oxygen species (ROS), electron paramagnetic resonance (EPR) spectroscopy was used. Additionally, mitochondrial ROS production was measured by adding inhibitors of electron transport chain complex III. There was an increased systemic ROS generation after the LIBR session from 0.837 ± 0.093 to 0.911 ± 0.099 µmol/l/min. However, no local or systemic time × condition interaction was detected for ROS production. Regarding mitochondrial ROS production, results were not different between the conditions. Although the low-load resistance exercise session with partial vascular occlusion elicited systemic increases of ROS production, no significant changes were seen on a local level. We assume that this ROS concentration might not be high enough to induce cellular damage but is rather involved in muscle remodulation. However, this needs to be confirmed by future research.

The perceptual responses to high-velocity, low-load and low-velocity, high-load resistance exercise in older adults

ABSTRACT The present study examined exercise affect during volume-load matched, high-velocity, low-load and low-velocity, high-load resistance exercise conditions in older adults. Ten older adults completed three sets of eight exercises on six separate occasions (three high-velocity, low-load and three low-velocity, high-load sessions) in a crossover study design. High-velocity, low-load was performed at 40% of predicted one repetition maximum, and low-velocity, high-load at 80%. The Physical Activity Affect Scale, Felt Arousal Scale, Feeling Scale, Rating of Perceived Exertion, Visual Analogue Scales, and the Physical Activity Enjoyment Scale examined exercise intensity and affect. There were moderate effects of exercise condition on positive exercise affect (P = 0.067; = 0.33), and trivial effects on negative exercise affect (P = 0.904; = 0.002). Rating of perceived exertion (P < 0.001; = 0.41) and fatigue (P = 0.012; = 0.52) were greater during low-velocity, high-load. Furthermore, high-velocity, low-load facilitated statistically insignificant, favourable changes (less exertion, more enjoyment etc.) for all other measures. These findings combined with emerging evidence that high-velocity, low-load is superior for improving muscle power and/or functional performance, indicates that high-velocity, low-load should be prescribed preferentially. However, both exercise conditions were enjoyed similarly, demonstrating that individual preference is an important consideration.

Early metabolic response after resistance exercise with blood flow restriction in well-trained men: a metabolomics approach.

The present study aimed to compare the early metabolic response between high-load resistance exercise (HL-RE) and low-load resistance exercise with blood flow restriction (LL-BFR). Nine young, well-trained men participated in a randomized crossover design in which each subject completed LL-BFR, HL-RE, or condition control (no exercise) with a 1-week interval between them. Blood samples were taken immediately before and 5 min after the exercise sessions. Nuclear magnetic resonance spectroscopy identified and quantified 48 metabolites, 6 of which presented significant changes among the exercise protocols. The HL-RE promoted a higher increase in pyruvate, lactate, and alanine compared with the LL-BFR and the control. HL-RE and LL-BFR promoted a higher increase in succinate compared with the control; however, there was no difference between HL-RE and LL-BFR. Also, while there was no difference in acetoacetate between HL-RE and LL-BFR, a greater decrease was observed in both compared with the control. Finally, LL-BFR promoted a greater decrease in choline compared with the control. In conclusion, this study provides by metabolomics a new insight in metabolic response between LL-BFR and HL-RE by demonstrating a distinct response to some metabolites that are not commonly analyzed.

Movement velocity during high- and low-velocity resistance exercise protocols in older adults

The primary aim of the present study was to determine the actual movement velocity of high-velocity, low-load (HVLL) and low-velocity, high-load (LVHL) resistance exercise in a group of older adults. The secondary aim was to examine the differences in velocities produced between male and females. In a crossover study design, four males (age: 67±3years) and five females (age: 68±2years) completed three sets of leg press, calf raise, leg curl, leg extension, chest press, seated row, bicep curl and tricep extension on six separate occasions (three HVLL and three LVHL sessions). The command “as fast as possible” was given for the concentric phase of HVLL, and 2s using a 60-bpm metronome controlled the concentric phase during LVHL. Participants had three days of recovery between each session, and a 7-day period before crossing over to the other protocol. Movement velocity was measured during the concentric and eccentric phases of resistance exercise using two-dimensional video analysis. The concentric phases for all exercises were significantly faster (P<0.001) during HVLL compared to LVHL. Furthermore, males produced significantly greater velocities than females during the concentric phase of the chest press, seated row, bicep curl, and tricep extension for both HVLL and LVHL (P<0.05). These protocols provide a simple solution for exercise professionals to ensure that older adults are training at desired velocities when carrying out resistance exercise, without the need for equipment that measures velocity.

Impact of Resistance Training on Skeletal Muscle Mitochondrial Biogenesis, Content, and Function.

Skeletal muscle metabolic and contractile properties are reliant on muscle mitochondrial and myofibrillar protein turnover. The turnover of these specific protein pools is compromised during disease, aging, and inactivity. Oppositely, exercise can accentuate muscle protein turnover, thereby counteracting decay in muscle function. According to a traditional consensus, endurance exercise is required to drive mitochondrial adaptations, while resistance exercise is required to drive myofibrillar adaptations. However, concurrent practice of traditional endurance exercise and resistance exercise regimens to achieve both types of muscle adaptations is time-consuming, motivationally demanding, and contended to entail practice at intensity levels, that may not comply with clinical settings. It is therefore of principle interest to identify effective, yet feasible, exercise strategies that may positively affect both mitochondrial and myofibrillar protein turnover. Recently, reports indicate that traditional high-load resistance exercise can stimulate muscle mitochondrial biogenesis and mitochondrial respiratory function. Moreover, fatiguing low-load resistance exercise has been shown capable of promoting muscle hypertrophy and expectedly entails greater metabolic stress to potentially enhance mitochondrial adaptations. Consequently, fatiguing low-load resistance exercise regimens may possess the ability to stimulate muscle mitochondrial adaptations without compromising muscle myofibrillar accretion. However, the exact ability of resistance exercise to drive mitochondrial adaptations is debatable, not least due to some methodological challenges. The current review therefore aims to address the evidence on the effects of resistance exercise on skeletal muscle mitochondrial biogenesis, content and function. In prolongation, a perspective is taken on the specific potential of low-load resistance exercise on promoting mitochondrial adaptations.

Effects of drop sets with resistance training on increases in muscle CSA, strength, and endurance: a pilot study

ABSTRACTTo investigate the effects of a single high-load (80% of one repetition maximum [1RM]) set with additional drop sets descending to a low-load (30% 1RM) without recovery intervals on muscle strength, endurance, and size in untrained young men. Nine untrained young men performed dumbbell curls to concentric failure 2–3 days per week for 8 weeks. Each arm was randomly assigned to one of the following three conditions: 3 sets of high-load (HL, 80% 1RM) resistance exercise, 3 sets of low-load [LL, 30% 1RM] resistance exercise, and a single high-load (SDS) set with additional drop sets descending to a low-load. The mean training time per session, including recovery intervals, was lowest in the SDS condition. Elbow flexor muscle cross-sectional area (CSA) increased similarly in all three conditions. Maximum isometric and 1RM strength of the elbow flexors increased from pre to post only in the HL and SDS conditions. Muscular endurance measured by maximum repetitions at 30% 1RM increased only in the LL and SDS conditions. A SDS resistance training program can simultaneously increase muscle CSA, strength, and endurance in untrained young men, even with lower training time compared to typical resistance exercise protocols using only high- or low-loads.

Postexercise blood flow restriction does not enhance muscle hypertrophy induced by multiple-set high-load resistance exercise.

To test the applicability of postexercise blood flow restriction (PEBFR) in practical training programmes, we investigated whether PEBFR enhances muscle hypertrophy induced by multiple-set high-load resistance exercise (RE). Seven men completed an eight-week RE programme for knee extensor muscles. Employing a within-subject design, one leg was subjected to RE+PEBFR, whereas contralateral leg to RE only. On each exercise session, participants performed three sets of unilateral knee extension exercise at approximately 70% of their one-repetition maximum for RE leg first, and then performed three sets for RE+PEBFR leg. Immediately after completion of the third set, the proximal portion of the RE+PEBFR leg was compressed with an air-pressure cuff for 5min at a pressure ranging from 100 to 150mmHg. If participants could perform 10 repetitions for three sets in two consecutive exercise sessions, the work load was increased by 5% at the next exercise session. Muscle thickness and strength of knee extensor muscles were measured before and after the eight-week training period and after the subsequent eight-week detraining period. There was a main effect of time but no condition×time interaction or main effect of condition for muscle thickness and strength. Both muscle thickness and strength increased after the training period independent of the condition. This result suggests that PEBFR would not be an effective training method at least in an early phase of adaptation to high-load resistance exercise.

Blood flow restriction increases metabolic stress but decreases muscle activation during high-load resistance exercise.

We investigated differences in metabolic stress (lactate) and muscle activation (electromyography; EMG) when high-load resistance exercise (HL) is compared with a condition in which blood flow restriction (BFR) is applied during the exercise or during the rest interval. Twelve participants performed HL with BFR during the intervals (BFR-I), during the set (BFR-S), and without BFR. Each condition consisted of 3 sets of 8 repetitions with knee extension at 70% of 1-repetition maximum. Lactate and root mean square (RMS) from the surface EMG of the vastus lateralis were calculated. Lactate increased in all protocols but was higher with BFR-I than with BFR-S and HL. RMS decreased under all conditions, with a larger effect size in BFR-I (1.47) than in BFR-S (0.66) and HL (0.59). BFR-I increases lactate, possibly as a result of reduced restoration of ATP. Muscle activation seems to be impacted by mechanical stress but may be reduced by metabolic stress. Muscle Nerve 57: 107-111, 2018.

Can blood flow restriction augment muscle activation during high-load training?

Blood flow restriction has been shown to augment muscle activation and increase muscle size when combined with low-load training; however, much less is known on whether blood flow restriction can augment muscle activation during high-load exercise. To determine whether applying blood flow restriction can augment muscle activation with traditional high-load resistance exercise. Ten individuals completed two sets of elbow flexion exercise to volitional fatigue. The control arm rested for 3min between sets while the experimental arm had blood flow restriction applied for 3min. The blood flow restricted arm completed significantly fewer repetitions in set 2 in comparison with set 1 [set 1: 9 (1), set 2: 4 (1); P<0·001], whereas no meaningful differences were observed in the control arm [set 1: 8 (1), set 2: 7 (1); P=0·057]. There was no interaction for muscle activation (P=0·851) with both conditions significantly lower at the start of set 2 [87 (26)%] in comparison with the end of set 1 [106 (40)%] or end of set 2 [103 (33)%]. The application of blood flow restriction does not augment muscle activation present with high-load exercise and would seem unlikely to induce greater muscle hypertrophy.

Upper body muscle activation during low-versus high-load resistance exercise in the bench press

OBJECTIVE: The purpose of this study was to compare activation of the upper body musculature during the barbell bench press at varying training intensities. METHODS: Twelve young, resistance-trained men performed sets of the bench press to momentary muscular failure with two different loads: a high-load (HIGH) set at 80% of 1RM and a low-load (LOW) set at 50% 1RM. Exercise order was counterbalanced so that half the subjects performed the LOW condition first and the other half performed the HIGH first. Surface electromyography (EMG) was used to assess mean, peak, and iEMG muscle activation of the anterior deltoid, triceps brachii, and sternal and clavicular heads of the pectoralis major. RESULTS: The main effects for trials were significant for mean EMG ( p< 0.001) and iEMG matched ( p< 0.001) favoring HIGH and iEMG total favoring LOW (p = 0.001) across all muscle groups in both conditions with varying effect sizes. All other main effects and interactions were not statistically significant. CONCLUSION: Despite similaritiesin peak EMG amplitude, the greater results for mean and iEMG matched in HIGH suggests that heavier loads may produce greater muscle activation.

Blood Flow Restricted Exercise Compared to High Load Resistance Exercise During Unloading.

Bed rest studies have shown that high load (HL) resistance training can mitigate the loss of muscle size and strength during musculoskeletal unloading; however, not all individuals are able to perform HL resistance exercise. Blood flow restricted (BFR) resistance exercise may be a novel way to prevent maladaptation to unloading without requiring HL exercise equipment. This study evaluated the muscular training adaptations to HL and BFR resistance training during unilateral lower limb suspension (ULLS), a human limb unloading model. ULLS allows for evaluation of exercise training in both weight-bearing and nonweight-bearing legs within the same individual. There were 13 participants who completed 25 d of ULLS and were counterbalanced to: 1) HL, N = 6; or 2) BFR, N = 7, training groups. During ULLS, HL and BFR performed unilateral leg press and heel raise exercise (3 d/wk). In weight-bearing legs, both HL and BFR increased knee extensor muscle cross-sectional area (CSA) and strength. In nonweight-bearing legs, knee extensor CSA and strength increased only in HL and decreased with BFR. HL and BFR resistance exercise were both effective exercise programs for the weight-bearing leg. However, BFR exercise was not as effective as HL resistance exercise in the nonweight-bearing leg. These data show that exercise that improved muscle CSA and strength in ambulatory weight-bearing conditions was not sufficient to maintain muscle function during unloading. For the preservation of muscle CSA and strength, BFR exercise should be considered an adjunct but not a primary exercise countermeasure for future space missions. Hackney KJ, Downs ME, Ploutz-Snyder L. Blood flow restricted exercise compared to high load resistance exercise during unloading. Aerosp Med Hum Perform. 2016; 87(8):688-696.

Acute Inflammatory Response to Low-, Moderate-, and High-Load Resistance Exercise in Women With Breast Cancer-Related Lymphedema.

Background. Resistance exercise is emerging as a potential adjunct therapy to aid in the management of breast cancer–related lymphedema (BCRL). However, the mechanisms underlying the relationships between the acute and long-term benefits of resistance exercise on BCRL are not well understood. Purpose. To examine the acute inflammatory response to upper-body resistance exercise in women with BCRL and to compare these effects between resistance exercises involving low, moderate, and high loads. The impact on lymphedema status and associated symptoms was also compared. Methods. A total of 21 women, 62 ± 10 years old, with BCRL participated in the study. Participants completed low-load (15-20 repetition maximum [RM]), moderate-load (10-12 RM), and high-load (6-8 RM) exercise sessions consisting of 3 sets of 6 upper-body resistance exercises. Sessions were completed in a randomized order separated by a 7- to 10-day wash-out period. Venous blood samples were obtained to assess markers of exercise-induced muscle damage and inflammation. Lymphedema status was assessed using bioimpedance spectroscopy and arm circumferences, and associated symptoms were assessed using Visual Analogue Scales for pain, heaviness, and tightness. Measurements were conducted before and 24 hours after the exercise sessions. Results. No significant changes in creatine kinase, C-reactive protein, interleukin-6, and tumor necrosis factor-α were observed following the 3 resistance exercise sessions. There were no significant changes in arm swelling or symptom severity scores across the 3 resistance exercise conditions. Conclusions. The magnitude of acute exercise-induced inflammation following upper-body resistance exercise in women with BCRL does not vary between resistance exercise loads.

Effectiveness of blood flow restricted exercise compared with standard exercise in patients with recurrent low back pain: study protocol for a randomized controlled trial

BackgroundLow back pain is a highly prevalent condition in the United States and has a staggeringly negative impact on society in terms of expenses and disability. It has previously been suggested that rehabilitation strategies for persons with recurrent low back pain should be directed to the medial back muscles as these muscles provide functional support of the lumbar region. However, many individuals with low back pain cannot safely and effectively induce trunk muscle adaptation using traditional high-load resistance exercise, and no viable low-load protocols to induce trunk extensor muscle adaptation exist. Herein, we present the study protocol for a randomized controlled trial that will investigate the “cross-transfer” of effects of a novel exercise modality, blood flow restricted exercise, on cross-sectional area (primary outcome), strength and endurance (secondary outcomes) of trunk extensor muscles, as well as the pain, disability, and rate of recurrence of low back pain (tertiary outcomes).Methods and study designThis is a single-blinded, single-site, randomized controlled trial. A minimum of 32 (and up to 40) subjects aged 18 to 50 years with recurrent low back pain and poor trunk extensor muscle endurance will be recruited, enrolled and randomized. After completion of baseline assessments, participants will be randomized in a 1:1 ratio to receive a 10-week resistance exercise training program with blood flow restriction (BFR exercise group) or without blood flow restriction (control exercise group). Repeat assessments will be taken immediately post intervention and at 12 weeks after the completion of the exercise program. Furthermore, once every 4 weeks during a 36-week follow-up period, participants will be asked to rate their perceived disability and back pain over the past 14 days.DiscussionThis study will examine the potential for blood flow restricted exercise applied to appendicular muscles to result in a “cross-transfer” of therapeutic effect to the lumbar musculature in individuals with low back pain. The results of this study will provide important insights into the effectiveness of this novel exercise modality, which could potentially provide the foundation for a cost-effective and easy-to-implement rehabilitation strategy to induce muscle adaptation in the absence of high mechanical and compressive loading on the spine.Trial registrationThis trial is registered with ClinicalTrials.gov (registration number: NCT02308189, date of registration: 2 December 2014).

Impact of resistance exercise on ribosome biogenesis is acutely regulated by post-exercise recovery strategies.

Muscle hypertrophy occurs following increased protein synthesis, which requires activation of the ribosomal complex. Additionally, increased translational capacity via elevated ribosomal RNA (rRNA) synthesis has also been implicated in resistance training-induced skeletal muscle hypertrophy. The time course of ribosome biogenesis following resistance exercise (RE) and the impact exerted by differing recovery strategies remains unknown. In the present study, the activation of transcriptional regulators, the expression levels of pre-rRNA, and mature rRNA components were measured through 48h after a single-bout RE. In addition, the effects of either low-intensity cycling (active recovery, ACT) or a cold-water immersion (CWI) recovery strategy were compared. Nine male subjects performed two bouts of high-load RE randomized to be followed by 10min of either ACT or CWI. Muscle biopsies were collected before RE and at 2, 24, and 48h after RE. RE increased the phosphorylation of the p38-MNK1-eIF4E axis, an effect only evident with ACT recovery. Downstream, cyclin D1 protein, total eIF4E, upstream binding factor 1 (UBF1), and c-Myc proteins were all increased only after RE with ACT. This corresponded with elevated abundance of the pre-rRNAs (45S, ITS-28S, ITS-5.8S, and ETS-18S) from 24h after RE with ACT. In conclusion, coordinated upstream signaling and activation of transcriptional factors stimulated pre-rRNA expression after RE. CWI, as a recovery strategy, markedly blunted these events, suggesting that suppressed ribosome biogenesis may be one factor contributing to the impaired hypertrophic response observed when CWI is used regularly after exercise.

Kaatsu training to enhance physical function of older adults with knee osteoarthritis: Design of a randomized controlled trial

As the U.S. population ages, efficacious interventions are needed to manage pain and maintain physical function among older adults with osteoarthritis (OA). Skeletal muscle weakness is a primary contributory factor to pain and functional decline among persons with OA, thus interventions are needed that improve muscle strength. High-load resistance exercise is the best-known method of improving muscle strength; however high-compressive loads commonly induce significant joint pain among persons with OA. Thus interventions with low-compressive loads are needed which improve muscle strength while limiting joint stress. This study is investigating the potential of an innovative training paradigm, known as Kaatsu, for this purpose. Kaatsu involves performing low-load exercise while externally-applied compression partially restricts blood flow to the active skeletal muscle. The objective of this randomized, single-masked pilot trial is to evaluate the efficacy and feasibility of chronic Kaatsu training for improving skeletal muscle strength and physical function among older adults. Participants aged≥60years with physical limitations and symptomatic knee OA will be randomly assigned to engage in a 3-month intervention of either (1) center-based, moderate-load resistance training, or (2) Kaatsu training matched for overall workload. Study dependent outcomes include the change in 1) knee extensor strength, 2) objective measures of physical function, and 3) subjective measures of physical function and pain. This study will provide novel information regarding the therapeutic potential of Kaatsu training while also informing about the long-term clinical viability of the paradigm by evaluating participant safety, discomfort, and willingness to continually engage in the intervention.

Increased resistance during jump exercise does not enhance cortical bone formation.

This study sought to elucidate the effects of a low- and high-load jump resistance exercise (RE) training protocol on cortical bone of the tibia and femur mid-diaphyses. Sprague-Dawley rats (male, 6 months old) were randomly assigned to high-load RE (HRE; n = 16), low-load RE (LRE; n = 15), or cage control (CC; n = 11) groups. Animals in the HRE and LRE groups performed 15 sessions of jump RE for 5 wk. Load in the HRE group was progressively increased from 80 g added to a weighted vest (50 repetitions) to 410 g (16 repetitions). The LRE rats completed the same protocol as the HRE group (same number of repetitions), with only a 30-g vest applied. Low- and high-load jump RE resulted in 6%-11% higher cortical bone mineral content and cortical bone area compared with controls, as determined by in vivo peripheral quantitative computed tomography measurements. In the femur, however, only LRE demonstrated improvements in cortical volumetric bone mineral density (+11%) and cross-sectional moment of inertia (+20%) versus the CC group. The three-point bending to failure revealed a marked increase in tibial maximum force (25%-29%), stiffness (19%-22%), and energy to maximum force (35%-55%) and a reduction in elastic modulus (-11% to 14%) in both LRE and HRE compared with controls. Dynamic histomorphometry assessed at the tibia mid-diaphysis determined that both LRE and HRE resulted in 20%-30% higher periosteal mineralizing surface versus the CC group. Mineral apposition rate and bone formation rate were significantly greater in animals in the LRE group (27%, 39%) than those in the HRE group. These data demonstrate that jump training with minimal loading is equally, and sometimes more, effective at augmenting cortical bone integrity compared with overload training in skeletally mature rats.

High-load resistance exercise with superimposed vibration and vascular occlusion increases critical power, capillaries and lean mass in endurance-trained men

It is a widely accepted premise in the scientific community and by athletes alike, that adding resistance exercise to a regular regimen of endurance training increases endurance performance in endurance-trained men. However, critical power (CP), capillarization, and myofiber size remain unaffected by this addition. Therefore, we tested whether the superimposition of resistance exercise with whole-body vibration and vascular occlusion (vibroX) would improve these variables in endurance-trained males relative to resistance exercise alone. Twenty-one young, endurance-trained males were randomly assigned either to a vibroX (n = 11) or resistance (n = 10) training group. Both groups trained in a progressive mode twice a week for 8 weeks. Pre and post training, histochemical muscle characteristics, thigh muscle size, endurance and strength parameters were determined. vibroX increased CP (P = 0.001), overall capillary-to-fiber ratio (P = 0.001) and thigh lean mass (P < 0.001), while these parameters were unaffected by resistance training. The gain in CP by vibroX was positively correlated with the gain in capillarization (R(2) = 0.605, P = 0.008), and the gain in thigh lean mass was paralleled by increases in MyHC-1 and MyHC-2 fiber cross-sectional areas and strength. Maximum voluntary torque and the finite work capacity above CP (W') increased significantly only following resistance training. We achieved a proof of concept by demonstrating that modification of resistance exercise by superimposing side-alternating whole-body vibration and sustained vascular occlusion induced further improvements in CP, capillarization and hypertrophy, all of which were not observed with resistance training alone.

AB0799 Blood flow restriction: the future of musculoskeletal rehabilitation?

BackgroundMusculoskeletal disease has a significant burden on the health of the population, with loss of strength and function a common consequence. Rehabilitation using isometric resistance training is a widely established...