Energy expenditure during a Vinyasa yoga session.

BACKGROUND: Vinyasa yoga has been recently promoted as one of the most popular mindful exercises to improve overall health, including body weight management. The purpose of this study was to determine the metabolic response of 24 moderately trained individuals during a 90-min group Vinyasa yoga routine. METHODS: Heart rate (HR) time course of 12 males and 12 females (age: 39±7.33 years) was recorded during two group Vinyasa yoga sessions consisted of four sections (warm-up, high-intensity Surya Namaskar (HSN), no Surya Namaskar postures, and cool-down). Maximal oxygen uptake (V̇O2peak) and maximum HR had been estimated earlier after a maximal treadmill test. V̇O2 during Vinyasa yoga sessions was estimated from individual regression equations using the relationship of V̇O2 and HR values derived from V̇O2peak test, while the metabolic rate (kcal/min) was calculated from the relationship of HR and kcal/min. Total session energy consumption was the average value of the two yoga sessions. RESULTS: The 2 (gender) × 4 (sections) mixed ANOVA revealed no significant interaction between the two factors (P=0.101) for the mean metabolic rate (7.1±2.6 kcal/min). Mean metabolic rate thought was higher (P=0.015) in males compared to females at each section. Also, significant differences were found among the four Vinyasa yoga sections (P<0.001) in the rate of energy expenditure, with HSN presenting the highest mean values (P<0.05). CONCLUSIONS: It seems that systematic participation in Vinyasa yoga may effectively improve cardiorespiratory fitness and promote body weight loss, as an alternative method to traditional aerobic exercise.

Effects of Various Recovery Strategies on Repeated Bouts of Simulated Intermittent Activity.

Crowther, FA, Sealey, RM, Crowe, MJ, Edwards, AM, and Halson, SL. Effects of various recovery strategies on repeated bouts of simulated intermittent activity. J Strength Cond Res 33(7): 1781-1794, 2019-A large variety of recovery strategies are used between and after bouts of exercise to maximize performance and perceptual recovery, with limited conclusive evidence regarding the effectiveness of these strategies. The aim of this study was to compare 5 postexercise recovery strategies (cold water immersion, contrast water therapy, active recovery, a combined cold water immersion and active recovery, and a control condition) to determine which is most effective for the recovery of performance, perceptual, and flexibility measures during and after repeated bouts of simulated small-sided team sport demands. Fourteen recreationally active males (mean ± SD; age: 26 ± 6 years; height: 180 ± 5 cm; mass: 81 ± 9 kg) undertook repeated bouts of exercise, simulating a rugby sevens tournament day followed by the above listed recovery strategies (randomized, 1 per week). Perceptual, performance, and flexibility variables were measured immediately before, 5 minutes after all 3 exercise bouts, and at 75 minutes after the first 2 exercise bouts. Contrast water therapy was found to be superior to active at 75 minutes after bout 2 and 5 minutes after bout 3 for repeated-sprint ability and relative average power. The combined recovery strategy was superior to active for repeated-sprint ability at 5 minutes after bout 3; relative best power at 5 minutes after bout 2; total quality recovery before bout 2, 75 minutes after bout 2, and before bout 3; was superior to active for muscle soreness from 75 minutes after bout 1 and for the remainder of the day; and was superior to the control at 75 minutes after bout 1, 75 minutes after bout 2, and before bout 3. The active recovery was detrimental to total sprint time and relative average power at 75 minutes after bout 2 and 5 minutes after bout 3 in comparison with contrast water therapy and the control (not relative average power). Relative average power was decreased after active at 5 minutes after bout 2 in comparison with the combined recovery strategy and the control. Relative average power after cold water immersion was decreased at 75 minutes after bout 2 in comparison with the control and contrast water therapy. Total quality recovery was significantly reduced after active in comparison with the combined recovery strategy before bout 2, 75 minutes after bout 2, and before bout 3. Muscle soreness was also significantly increased after active recovery at 75 minutes after bout 1 and for the remainder of the day in comparison with the combined recovery strategy and was increased at 5 minutes after bout 3 in comparison with the control. Active recovery is not recommended because of the detrimental performance and perceptual results noted. As no recovery strategies were significantly better than the control condition for performance recovery and the combined recovery strategy is the only superior recovery strategy in comparison with the control for perceptual recovery (muscle soreness only), it is difficult to recommend a recovery strategy that should be used for both performance and perceptual recovery. Thus, based on the methodology and findings of this study unless already in use by athletes, no water immersion recovery strategies are recommended in preference to a control because of the resource-intensive (time and equipment) nature of water immersion recovery strategies.

Efficacy of Various Cooling Techniques During Exercise in Persons With Spinal Cord Injury: A Pilot Crossover Intervention Study.

Background: Decentralization of the sympathetic nervous system in persons with spinal cord injury (SCI) results in impaired vasomotor and sudomotor activity and, subsequently, impaired thermoregulatory capacity during exercise in the heat. Hyperthermia can be life-threatening and, as such, cooling interventions are needed to prevent this sequela. Objectives: To measure change in core temperature (ΔTC) over time during exercise in normothermic and high ambient heat conditions to compare thermoregulatory capacity in persons with varying degrees of intact vasomotor and sudomotor activity and to determine the efficacy of three cooling interventions in mitigating TC rise. Methods: Three persons participated: a 51-year-old with complete (AIS A) tetraplegia (TP), a 32-year-old with AIS A paraplegia (PP), and a 40-year-old without SCI (AB). Each exercised for 30 minutes on a wheelchair treadmill propelled at 30 revolutions per minute under five different conditions: (1) cool (C) = 75°F without cooling, (2) hot (H) = 90°F without cooling, (3) 90°F with cooling vest (CV), (4) 90°F with water spray (WS), and (5) 90°F with ice slurry ingestion (IS). ΔTC was compared for all conditions in all participants. Results: ΔTC in the C and H conditions was proportional to the neurological level of injury, with Tc rising highest in the TP followed by the PP then AB. WS was most efficacious at mitigating rise in TC followed by IS and CV in TP and PP. None of the cooling interventions provided an added TC cooling effect in AB. Conclusion: WS was most efficacious at mitigating rise in TC in TP>PP during exercise in the heat and should be studied in a larger SCI population.

Precooling, Exertional Heatstroke Risk Factors, and Postexercise Cooling Rates.

BACKGROUND: Precooling (PC) before exercise may help prevent severe hyperthermia and exertional heatstroke (EHS). Before clinicians can advocate PC as an EHS prevention strategy, it must effectively mitigate factors associated with EHS development while not lessening the effectiveness of EHS treatment. Therefore, this study determined if PC affected rectal temperature (Trec), body heat storage, heart rate (HR), ratings of perceived exertion (RPE), thermal sensation, sweat rate, and postexercise cold-water immersion (CWI) Trec cooling rates.METHODS: In this randomized, crossover, counterbalanced study, 12 subjects (6 men, 6 women; age = 22 ± 2 yr; mass = 73.5 ± 7.9 kg; height = 171 ± 7 cm) underwent 15 min of CWI (10.0 ± 0.03°C) in an environmental chamber (38.6 ± 0.6°C; 36 ± 2% humidity). After a 10-min rest, they exercised to a Trec of 39.5°C. Subsequently, they underwent CWI (9.99 ± 0.03°C) until Trec reached 38°C. On control (CON) days, the same procedures occurred without the 15-min PC intervention. Trec, HR, thermal sensation, and RPE were measured at various times before, during, and after exercise.RESULTS: PC lowered body heat storage and Trec by 15.7 ± 15.0 W · m-2 and 0.42 ± 0.40°C, respectively, before exercise. Subjects exercised significantly longer (PC = 66.7 ± 16.3 min, CON = 45.7 ± 9.5 min) and at lower Trec (∼0.5 ± 0.5°C) and HR (∼10 ± 7 bpm) following PC. PC significantly lowered sweat rate (PC = 1.02 ± 0.31 L · h-1, CON = 1.22 ± 0.39 L · h-1), but did not affect RPE or CWI cooling rates (PC = 0.18 ± 0.14°C · min-1; CON = 0.19 ± 0.05°C · min-1). Thermal sensation significantly differed between conditions only at pre-exercise (PC = 3 ± 1, CON = 5 ± 0.5).DISCUSSION: PC delayed severe hyperthermia and mitigated dehydration without affecting thermal perception or cooling rates posthyperthermia. PC may help prevent dangerous hyperthermia in athletes.Wohlfert TM, Miller KC. Precooling, exertional heatstroke risk factors, and postexercise cooling rates. Aerosp Med Hum Perform. 2019; 90(1):12-17.

Consensus recommendations on training and competing in the heat.

Exercising in the heat induces thermoregulatory and other physiological strain that can lead to impairments in endurance exercise capacity. The purpose of this consensus statement is to provide up-to-date recommendations to optimise performance during sporting activities undertaken in hot ambient conditions. The most important intervention one can adopt to reduce physiological strain and optimise performance is to heat acclimatise. Heat acclimatisation should comprise repeated exercise-heat exposures over 1-2 weeks. In addition, athletes should initiate competition and training in a euhydrated state and minimise dehydration during exercise. Following the development of commercial cooling systems (eg, cooling-vest), athletes can implement cooling strategies to facilitate heat loss or increase heat storage capacity before training or competing in the heat. Moreover, event organisers should plan for large shaded areas, along with cooling and rehydration facilities, and schedule events in accordance with minimising the health risks of athletes, especially in mass participation events and during the first hot days of the year. Following the recent examples of the 2008 Olympics and the 2014 FIFA World Cup, sport governing bodies should consider allowing additional (or longer) recovery periods between and during events, for hydration and body cooling opportunities, when competitions are held in the heat.

Single muscle fiber gene expression with run taper.

This study evaluated gene expression changes in gastrocnemius slow-twitch myosin heavy chain I (MHC I) and fast-twitch (MHC IIa) muscle fibers of collegiate cross-country runners (n = 6, 20±1 y, VO2max = 70±1 ml•kg-1•min-1) during two distinct training phases. In a controlled environment, runners performed identical 8 kilometer runs (30:18±0:30 min:s, 89±1% HRmax) while in heavy training (∼72 km/wk) and following a 3 wk taper. Training volume during the taper leading into peak competition was reduced ∼50% which resulted in improved race times and greater cross-section and improved function of MHC IIa fibers. Single muscle fibers were isolated from pre and 4 hour post run biopsies in heavily trained and tapered states to examine the dynamic acute exercise response of the growth-related genes Fibroblast growth factor-inducible 14 (FN14), Myostatin (MSTN), Heat shock protein 72 (HSP72), Muscle ring-finger protein-1 (MURF1), Myogenic factor 6 (MRF4), and Insulin-like growth factor 1 (IGF1) via qPCR. FN14 increased 4.3-fold in MHC IIa fibers with exercise in the tapered state (P<0.05). MSTN was suppressed with exercise in both fiber types and training states (P<0.05) while MURF1 and HSP72 responded to running in MHC IIa and I fibers, respectively, regardless of training state (P<0.05). Robust induction of FN14 (previously shown to strongly correlate with hypertrophy) and greater overall transcriptional flexibility with exercise in the tapered state provides an initial molecular basis for fast-twitch muscle fiber performance gains previously observed after taper in competitive endurance athletes.

The impact of high-intensity intermittent exercise on resting metabolic rate in healthy males.

INTRODUCTION: High-intensity intermittent exercise training (HIT) may favourably alter body composition despite low training volumes and predicted energy expenditure (EE). PURPOSE: To characterise the acute impact of two common HIT protocols on EE and post-exercise oxygen consumption (11 h EPOC). METHODS: Oxygen consumption (l min(-1)), respiratory exchange ratio (RER) and EE were measured in nine healthy, lean males over 12 h under three conditions: control (CON), HIT1 (10 × 1 min high-intensity cycling bouts followed by 1 min rest) and HIT2 (10 × 4 min high-intensity cycling bouts followed by 2 min rest). RESULTS: Total exercise period EE during HIT1 (1,151 ± 205 kJ) (mean ± SD) was significantly lower than HIT2 (2,788 ± 322 kJ; p < 0.001). EE within the 60 min after exercise was significantly albeit marginally higher after HIT1 (388 ± 44 kJ; p = 0.02) and HIT2 (389 ± 39 kJ; p = 0.01) compared with CON (329 ± 39 kJ), with no difference between exercise conditions (p = 0.778). RER during this period was significantly lower in HIT1 (0.78 ± 0.06; p = 0.011) and HIT2 (0.76 ± 0.04; p = 0.004) compared with CON (0.87 ± 0.06). During the 'slow phase' of EPOC (1.25-9.75 h), there were no significant differences in EE (p = 0.07) or RER (p = 0.173) between trials. CONCLUSIONS: Single HIT sessions notably increases EE during exertion; however, the influence on metabolic rate post-exercise is transient and relatively minor.

Session perceived exertion and affective responses to self-selected and imposed cycle exercise of the same intensity in young men.

Session perceived exertion (S-RPE) and session affective responses (S-AR) are post-exercise estimates of the global responses experienced during exercise. To compare S-RPE and S-AR to acute RPE (A-RPE) and acute AR (A-AR) during self-selected (SS) and imposed (IMP) exercise of the same workload. Thirty-two males (22.3 ± 2.2 years) performed two, 20-min cycle exercise trials. In the SS trial, subjects adjusted SS workload every 5 min. In the IMP trial, workload was automatically adjusted to the SS workload. Experimental (EXP, n = 16) subjects were unaware that workload was the same between the trials. Control (CON, n = 16) subjects were aware that both trials were of the same workload. A-RPE and A-AR were measured every 5 min using the OMNI Scale and Feeling Scale, respectively. Fifteen minutes following a cool-down, subjects rated S-RPE and S-AR. Session and exercise values were compared between trials and groups using ANOVA. No between-group differences were observed. There were no differences between the SS and IMP trials for S-RPE, A-RPE, S-AR and A-AR. For SS and IMP trials, S-RPE was greater than A-RPE (4.6 ± 1.5 vs. 3.9 ± 1.4; 4.3 ± 1.6 vs. 3.7 ± 1.4, respectively, p < 0.05). S-AR was greater than A-AR for the SS trial (1.9 ± 1.3 vs. 2.3 ± 1.5, p < 0.05), but not the IMP trial (1.9 ± 1.5 vs. 2.2 ± 1.4). A mismatch exists between the session and acute exercise values for RPE and AR during the SS cycle exercise in young males.