Are higher blood flow restriction pressures more beneficial when lower loads are used?

The application of blood flow restriction during low-load resistance exercise has been shown to induce muscle growth with high or low restriction pressures, however, loads lower than 20% one-repetition maximum (1RM) remain unexplored. Fourteen trained individuals completed six elbow flexion protocols involving three different loads (10%, 15%, and 20% 1RM) each of which was performed with either a low (40% arterial occlusion) or high (80% arterial occlusion) pressure. Pre- and post-measurements of surface electromyography (sEMG), isometric torque, and muscle thickness were analyzed. An interaction was present for torque (p < 0.001) and muscle thickness (p < 0.001) illustrating that all increases in pressure and/or load resulted in a greater fatigue and muscle thickness. There was no interaction for sEMG (p = 0.832); however, there were main effects of condition (p = 0.002) and time (p = 0.019) illustrating greater sEMG in the 20% 1RM conditions. Higher blood flow restriction pressures may be more beneficial for muscle growth when very low loads are used

The affective and behavioral responses to repeated “strength snacks”

Background A training program consisting of only one-repetition maximum (1RM) training results in similar strength adaptations as traditional resistance exercise. However, little is known regarding the affective or behavioral responses to this type of training. Aim To examine the affective and behavioral response to either a traditional resistance exercise program or a biweekly 1RM-training program. Methods Participants were trained for 8 weeks (2× per week). The HYPER group completed four sets of 8–12 repetitions; the 1RM group (TEST) worked up to a single maximal repetition. Results The TEST group felt more revitalized and had an increase in positive engagement during their first visit, whereas the HYPER group showed an increase in feelings of physical exhaustion during their first and last visits. There were no pre to post differences for the change in behavior or self-efficacy between groups. Conclusion 1RM training appears to elicit a more favorable affective response, compared with HYPER training, which may ultimately improve adherence to resistance-type exercise

The acute muscular response to two distinct blood flow restriction protocols

The purpose of this study was to determine acute physiological and perceptual responses to two commonly implemented blood flow restriction protocols. Using a within-subject design, 15 participants (age ∼25) performed four sets of unilateral elbow flexion with each arm. One arm exercised using a 3-cm elastic cuff inflated to 160 mmHg, whereas the other arm exercised using a 5-cm nylon cuff inflated to 40% of the individual’s arterial occlusion pressure. While both protocols elicited increases in acute muscle thickness [pre: 4.5 (0.2) cm, post: 5.0 (0.2) cm; p < 0.001] and electromyography amplitude [first 3 reps: 55 (5) %MVC; last 3 reps: 87 (10) %MVC], there were no differences between conditions. Both protocols produced decreases in post-exercise strength (pre: 70 Nm, post: 51 Nm; p < 0.001) with no difference between conditions. The nylon protocol resulted in more repetitions during sets 2 [13 (2) vs. 9 (4); p = 0.001] and 3 [10 (2) vs. 7 (4); p = 0.05], while producing lower levels of discomfort following each set (average 3 vs. 4; p < 0.05). In conclusion, both protocols produced similar acute responses thought to be important for promoting muscle growth. However, the use of arbitrary pressures may place some individuals under complete arterial occlusion which may increase the potential risk of an adverse event

Primary Hyperparathyroidism Influences the Expression of Inflammatory and Metabolic Genes in Adipose Tissue

Background: Primary hyperparathyroidism (PHPT) is characterised by increased production of parathyroid hormone (PTH) resulting in elevated serum calcium levels. The influence on bone metabolism with altered bone resorption is the most studied clinical condition in PHPT. In addition to this, patients with PHPT are at increased risk of non-skeletal diseases, such as impaired insulin sensitivity, arterial hypertension and increased risk of death by cardiovascular diseases (CVD), possibly mediated by a chronic low-grade inflammation. The aim of this study was to investigate whether adipose tissue reflects the low-grade inflammation observed in PHPT patients. Methodology/Principal Findings: Subcutaneous fat tissue from the neck was sampled from 16 non-obese patients with PHPT and from 16 patients operated for benign thyroid diseases, serving as weight-matched controls. RNA was extracted and global gene expression was analysed with Illumina BeadArray Technology. We found 608 differentially expressed genes (q-value,0.05), of which 347 were up-regulated and 261 were down-regulated. Gene ontology analysis showed that PHPT patients expressed increased levels of genes involved in immunity and defense (e.g. matrix metallopeptidase 9, S100 calcium binding protein A8 and A9, CD14, folate receptor 2), and reduced levels of genes involved in metabolic processes. Analysis of transcription factor binding sites present in the differentially expressed genes corroborated the up-regulation of inflammatory processes. Conclusions/Significance: Our findings demonstrate that PHPT strongly influences gene regulation in fat tissue, which may result in altered adipose tissue function and release of pathogenic factors that increase the risk of CVD

The short-term effect of high versus moderate protein intake on recovery after strength training in resistance-trained individuals

Background: Dietary protein intakes up to 2.9 g.kg-1.d-1 and protein consumption before and after resistance training may enhance recovery, resulting in hypertrophy and strength gains. However, it remains unclear whether protein quantity or nutrient timing is central to positive adaptations. This study investigated the effect of total dietary protein content, whilst controlling for protein timing, on recovery in resistance trainees. Methods: Fourteen resistance-trained individuals underwent two 10-day isocaloric dietary regimes with a protein content of 1.8 g.kg-1.d-1 (PROMOD) or 2.9 g.kg-1.d-1 (PROHIGH) in a randomised, counterbalanced, crossover design. On days 8-10 (T1-T3), participants undertook resistance exercise under controlled conditions, performing 3 sets of squat, bench press and bent-over rows at 80% 1 repetition maximum until volitional exhaustion. Additionally, participants consumed a 0.4 g.kg-1 whey protein concentrate/isolate mix 30 minutes before and after exercise sessions to standardise protein timing specific to training. Recovery was assessed via daily repetition performance, muscle soreness, bioelectrical impedance phase angle, plasma creatine kinase (CK) and tumor necrosis factor-α (TNF-α). Results: No significant differences were reported between conditions for any of the performance repetition count variables (p>0.05). However, within PROMOD only, squat performance total repetition count was significantly lower at T3 (19.7 ± 6.8) compared to T1 (23.0 ± 7.5; p=0.006). Pre and post-exercise CK concentrations significantly increased across test days (p≤0.003), although no differences were reported between conditions. No differences for TNF-α or muscle soreness were reported between dietary conditions. Phase angle was significantly greater at T3 for PROHIGH (8.26 ± 0.82°) compared with PROMOD (8.08 ± 0.80°; p=0.012). Conclusions: When energy intake and peri-exercise protein intake was controlled for, a short term PROHIGH diet did not improve markers of muscle damage or soreness in comparison to a PROMOD approach following repeated days of intensive training. Whilst it is therefore likely that protein intakes (1.8g.kg-1.d-1) may be sufficient for resistance-trained individuals, it is noteworthy that both lower body exercise performance and bioelectrical phase angle were maintained with PROHIGH. Longer term interventions are warranted to determine whether PROMOD intakes are sufficient during prolonged training periods or when extensive exercise (e.g. training twice daily) is undertaken

A higher effort-based paradigm in physical activity and exercise for public health: making the case for a greater emphasis on resistance training

It is well known that physical activity and exercise is associated with a lower risk of a range of morbidities and all-cause mortality. Further, it appears that risk reductions are greater when physical activity and/or exercise is performed at a higher intensity of effort. Why this may be the case is perhaps explained by the accumulating evidence linking physical fitness and performance outcomes (e.g. cardiorespiratory fitness, strength, and muscle mass) also to morbidity and mortality risk. Current guidelines about the performance of moderate/vigorous physical activity using aerobic exercise modes focuses upon the accumulation of a minimum volume of physical activity and/or exercise, and have thus far produced disappointing outcomes. As such there has been increased interest in the use of higher effort physical activity and exercise as being potentially more efficacious. Though there is currently debate as to the effectiveness of public health prescription based around higher effort physical activity and exercise, most discussion around this has focused upon modes considered to be traditionally ‘aerobic’ (e.g. running, cycling, rowing, swimming etc.). A mode customarily performed to a relatively high intensity of effort that we believe has been overlooked is resistance training. Current guidelines do include recommendations to engage in ‘muscle strengthening activities’ though there has been very little emphasis upon these modes in either research or public health effort. As such the purpose of this debate article is to discuss the emerging higher effort paradigm in physical activity and exercise for public health and to make a case for why there should be a greater emphasis placed upon resistance training as a mode in this paradigm shift

INJURIES AND STRENGTH AND CONDITIONING PRACTICES IN COLLEGIATE TENNIS

Ecaterina Vasenina1, William B. Hammert2, Ryo Kataoka2, Scott J. Dankel3, Samuel L. Buckner2. 1University of Central Florida, Orlando, FL. 2University of South Florida, Tampa, FL. 3Rowan University, Glassboro, NJ. BACKGROUND: Little is known regarding the relationship between injury rates and strength and conditioning practices in collegiate tennis. METHODS: College tennis team coaches were surveyed on their injury rates and strength and conditioning practices over the past year. Coaches reported the number of ankle sprains, ankle fractures, thigh muscle strains, knee ligament strain, groin muscle strain, amongst others. Coaches were also surveyed (yes/no) on whether their training program included training related to upper body or lower body “strength”, “power”, “muscle growth”, and “maximal eccentric exercise”. Separate regression analyses were ran in the upper and lower body to examine the relationship between total injuries and participation in training focused on strength, power, growth and maximal eccentric exercise. RESULTS: A total of 111 coaches were surveyed. The most frequent injury observed were ankle sprains (144 injures), followed by paraspinal muscle strains (126 injuries), 95 internal or subacromial impingements, 82 thigh muscle strains, 75 groin muscle strains, and 68 abdominal muscle strains. When pooled, there were a total of 355 lower body injuries and 260 upper body injuries reported. Strength and conditioning practices explained 9.9% of the variance of injury rates in the upper body (R2= 0.099). The only significant predictor of upper body injury was participation in training related to upper body muscle growth (β= 1.613, p = 0.013). In addition, strength and conditioning practices explained 11.1% of the variance of injury rates in the lower body (R2= 0.111). The only significant predictor of lower body injury was participation in training related to lower body muscle growth (β= 1.687, p = 0.038). CONCLUSIONS: Results of the present study suggest that a focus on upper and lower body muscle hypertrophy may increase risk of injury in the sport of tennis. Future research should examine ways to reduce injuries in tennis and relationship between strength and conditioning exercises and injuries