No abstract

Key Points• The blood flow restriction (BFR) stimulus should be individualized for each participant. In particular, consideration should be given to the restrictive pressure applied and cuff width used.• BFR elicits the largest increases in muscular development when combined with low-load resistance exercise, though some benefits may be seen using BFR alone during immobilization or combined with low-workload cardiovascular exercise.• For healthy individuals, training adaptations are likely maximized by combining low-load BFR resistance exercise with traditional high-load resistance exercise. 2 AbstractA growing body of evidence supports the use of moderate blood flow restriction (BFR) combined with low-load resistance exercise to enhance hypertrophic and strength responses in skeletal muscle. Research also suggests that BFR during lowworkload aerobic exercise can result in small but significant morphological and strength gains, and BFR alone may attenuate atrophy during periods of unloading.While BFR appears to be beneficial for both clinical and athletic cohorts, there is currently no common consensus amongst scientists and practitioners regarding the best practice for implementing BFR methods. If BFR is not employed appropriately, there is a risk of injury to the participant. It is also important to understand how variations in the cuff application can affect the physiological responses and subsequent adaptation to BFR training. The optimal way to manipulate acute exercise variables, such as exercise type, load, volume, inter-set rest periods and training frequency, must also be considered prior to designing a BFR training program. The purpose of this review is to provide an evidence-based approach to implementing BFR exercise. These guidelines could be useful for practitioners using BFR training in either clinical or athletic settings, or for researchers in the design of future studies investigating BFR exercise.3

The present investigation compared responses in previously identified physiological, biochemical, and psychological markers of overreaching in triathletes. Sixteen experienced male triathletes (.VO(2max) [mean +/- SD] = 55.7 +/- 4.9 mL . kg (-1) . min (-1), age = 31.3 +/- 11.7 yr) were divided into matched groups according to physical and performance characteristics, and were randomly assigned to either intensified training (IT) or normal training (NT) groups. Physiological, biochemical, and psychological measures were taken at baseline, following four weeks of overload training and following a two-week taper. The IT group completed 290 % greater physical training load than the NT group during the overload period. The subjects completed a 3-km run time trial (3-km RTT) each week in order to assess the time course of change in endurance performance. 3-km RTT performance was significantly reduced (3.7 +/- 7.5 %; p < 0.05) following four weeks of overload training in the IT group confirming a state of overreaching. During the same period, 3-km RTT performance significantly improved in the NT group (3.0 +/- 1.1 %; p < 0.05). Following the two-week taper, 3-km RTT performance significantly improved in the IT group (7.0 +/- 5.6 %; p < 0.05). Hemoglobin concentration significantly decreased and urea increased in both groups during the overload period (p < 0.05). During the taper hemoglobin normalized with a greater increase in the IT group compared to the NT group (p < 0.05). A significant increase in free testosterone to cortisol ratio was also observed in the IT group compared to the NT group during the taper (p < 0.05). No significant changes were observed for any other biochemical variables during the period of investigation. The RESTQ-76 Sport questionnaire showed an impaired recovery-stress state with increased training load, which improved following the taper in the IT group (p < 0.05). These present results suggest that none of the physiological and biochemical variables measured in this study were effective for the early identification of overreaching in experienced triathletes. However, the RESTQ-76 Sport questionnaire may provide a practical tool for recognizing overreaching in its early stages. These findings have implications for monitoring training status in athletes in a practical training setting.

It is generally believed that optimal hypertrophic and strength gains are induced through moderate-or high-intensity resistance training, equivalent at least 60% of an individual's 1-repetition maximum (1RM). However, recent evidence suggests that similar adaptations are facilitated when low-intensity resistance exercise (~20-50% 1RM) is combined with blood flow restriction (BFR) to the working muscles. Although the mechanisms underpinning these responses are not yet firmly established, it appears that localized hypoxia created by BFR may provide an anabolic stimulus by enhancing the metabolic and endocrine response, and increase cellular swelling and signalling function following resistance exercise. Moreover, BFR has also been demonstrated to increase type II muscle fibre recruitment during exercise.However, inappropriate implementation of BFR can result in detrimental effects, including petechial haemorrhage and dizziness. Further, as BFR is limited to the limbs, the muscles of the trunk are unable to be trained under localized hypoxia. More recently, the use of systemic hypoxia via hypoxic chambers and devices has been investigated as a novel way to stimulate similar physiological responses to resistance training as BFR techniques. While little evidence is available, reports indicate that beneficial adaptations, similar to those induced by BFR, are possible using these methods. The use of systemic hypoxia allows large groups to train concurrently within a hypoxic chamber using multi-joint exercises. However, further scientific research is required to fully understand the mechanisms that cause augmented muscular changes during resistance exercise with a localized or systemic hypoxic stimulus.3

No abstract

These findings showed that each of the training load methods investigated are appropriate for quantifying endurance training dose and that submaximal HR and HRV may be useful for monitoring fitness and fatigue, respectively.

23!Objectives: This study aimed to collate current evidence regarding the efficacy of various blood flow 24! restriction (BFR) strategies for well-trained athletes, and to provide insight regarding how such 25! strategies can be used by these populations. 26!Design: Review article. 27! 44! 45!

Scott, BR, Slattery, KM, Sculley, DV, Lockhart, C, and Dascombe, BJ. Acute physiological responses to moderate-load resistance exercise in hypoxia. J Strength Cond Res 31(7): 1973-1981, 2017-This study assessed whether hypoxia augments anabolic responses to moderate-load resistance exercise. Fourteen trained men performed moderate-load resistance exercise in normoxia (NORM; fraction of inspired oxygen [FIO2] = 21%) and moderate-level hypoxia (MH; FIO2 = 16%). Exercise comprised 3 sets of 10 repetitions of squats and deadlifts at 60% of 1 repetition maximum, with 60-second interset rest. Blood lactate (BLa) was quantified after each exercise, whereas arterial oxygen saturation and heart rate (HR) were assessed after each set. Thigh circumference was measured before and after exercise. Muscle activation and oxygenation were monitored by surface electromyography (EMG) and near-infrared spectroscopy, respectively. Relative BLa concentrations were significantly higher following squats (p = 0.041) and deadlifts (p = 0.002) in MH than NORM. Arterial oxygen saturation was lower after each set in MH compared with NORM (p < 0.001), although HR and thigh circumference were not different between conditions. Integrated EMG was higher in MH than in NORM for the squat during several repetitions (p ≤ 0.032). Measures of muscle oxygen status were not significantly different between conditions (p ≥ 0.247). The main findings from this study suggest that hypoxia during moderate-load resistance exercise augments metabolite accumulation and muscle activation. However, a significant hypoxic dose was not measured at the muscle, possibly because of the moderate level of hypoxia used. The current data support previous hypotheses that have suggested hypoxia can augment some physiological responses that are important for muscular development, and may therefore provide benefit over the equivalent training in normoxia.