The aerobic dive limit (ADL) and the hypothesis that most dives are aerobic in nature have become fundamental to the understanding of diving physiology and to the interpretation of diving behavior ...and foraging ecology of marine mammals and seabirds. An ADL, the dive duration associated with the onset of post-dive blood lactate accumulation, has only been documented with blood lactate analyses in five species. Applications to other species have involved behavioral estimates or use of an oxygen store / metabolic rate formula. Both approaches have limitations, but have proved useful to the evaluation of the dive behavior and ecology of many species.
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•Aerobic dive limit (ADL): dive duration associated with the onset of post-dive blood lactate accumulation•ADL concept: most dives of marine mammals and seabirds are aerobic•ADL only determined with blood lactate measurements in five species•Physiological basis of the ADL: muscle O2 depletion and subsequent glycolysis•Estimation of ADL in other species → widespread application to interpretation of dive behavior and ecology•Behavioral estimation of the ADL: dive duration distribution and dive duration-surface interval criteria•Mathematical estimation of ADL: O2 stores / diving metabolic rate
Olney, N, Wertz, T, LaPorta, Z, Mora, A, Serbas, J, and Astorino, TA. Comparison of acute physiological and psychological responses between moderate-intensity continuous exercise and three regimes of ...high intensity interval training. J Strength Cond Res 32(8): 2130-2138, 2018-High-intensity interval training (HIIT) elicits similar physiological adaptations as moderate-intensity continuous training (MICT) despite less time commitment. However, there is debate whether HIIT is more aversive than MICT. This study compared physiological and perceptual responses between MICT and 3 regimes of HIIT. Nineteen active adults (age = 24.0 ± 3.3 years) unfamiliar with HIIT initially performed ramp exercise to exhaustion to measure maximal oxygen uptake (VCombining Dot AboveO2max) and determine workload for subsequent sessions, whose order was randomized. Sprint interval training (SIT) consisted of six 20-second bouts of "all-out" cycling at 140% of maximum watts (Wmax). Low-volume HIIT (HIITLV) and high-volume HIIT (HIITHV) consisted of eight 60-second bouts at 85% Wmax and six 2-minute bouts at 70% Wmax, respectively. Moderate-intensity continuous training consisted of 25 minutes at 40% Wmax. Across regimes, work was not matched. Heart rate (HR), VCombining Dot AboveO2, blood lactate concentration (BLa), affect, and rating of perceived exertion (RPE) were assessed during exercise. Ten minutes postexercise, Physical Activity Enjoyment (PACES) was measured via a survey. Results revealed significantly higher (p ≤ 0.05) VCombining Dot AboveO2, HR, BLa, and RPE in SIT, HIITLV, and HIITHV vs. MICT. Despite a decline in affect during exercise (p < 0.01) and significantly lower affect (p ≤ 0.05) during all HIIT regimes vs. MICT at 50, 75, and 100% of session duration, PACES was similar across regimes (p = 0.65), although it was higher in women (p = 0.03). Findings from healthy adults unaccustomed to interval training demonstrate that HIIT and SIT are perceived as enjoyable as MICT despite being more aversive.
The present study investigated the effects of high-intensity intermittent training (HIIT) on lower- and upper-body graded exercise and high-intensity intermittent exercise (HIIE, four Wingate bouts) ...performance, and on physiological and muscle damage markers responses in judo athletes.
Thirty-five subjects were randomly allocated to a control group (n = 8) or to one of the following HIIT groups (n = 9 for each) and tested pre- and post-four weeks (2 training d·wk(-1)): (1) lower-body cycle-ergometer; (2) upper-body cycle-ergometer; (3) uchi-komi (judo technique entrance). All HIIT were constituted by two blocks of 10 sets of 20 s of all out effort interspersed by 10 s set intervals and 5-min between blocks.
For the upper-body group there was an increase in maximal aerobic power in graded upper-body exercise test (12.3%). The lower-body group increased power at onset blood lactate in graded upper-body exercise test (22.1%). The uchi-komi group increased peak power in upper- (16.7%) and lower-body (8.5%), while the lower-body group increased lower-body mean power (14.2%) during the HIIE. There was a decrease in the delta blood lactate for the uchi-komi training group and in the third and fourth bouts for the upper-body training group. Training induced testosterone-cortisol ratio increased in the lower-body HIIE for the lower-body (14.9%) and uchi-komi (61.4%) training groups.
Thus, short-duration low-volume HIIT added to regular judo training was able to increase upper-body aerobic power, lower- and upper-body HIIE performance.
Endothelial dysfunction is the first pathophysiological step of atherosclerosis, which is responsible for 90% of strokes. Exercise programs aim to reduce the risk of developing stroke; however, the ...majority of the beneficial factors of exercise are still unknown. Endothelial shear stress (ESS) is associated with endothelial homeostasis. Unfortunately, ESS has not been characterized during different exercise modalities and intensities in the carotid artery. Therefore, the purpose of this study was to determine exercise-induced blood flow patterns in the carotid artery. Fourteen apparently healthy young adults (males = 7, females = 7) were recruited for this repeated measures study design. Participants completed maximal oxygen consumption (VO2max) tests on a Treadmill, Cycle-ergometer, and Arm-ergometer, and 1-repetition maximum (1RM) tests of the Squat, Bench Press (Bench), and Biceps Curl (Biceps) on separate days. Thereafter, participants performed each exercise at 3 different exercise intensities (low, moderate, high) while a real-time ultrasound image and blood flow of the carotid artery was obtained. Blood flow patterns were assessed by estimating ESS
Womersley's estimation and turbulence
Reynold's number (Re). Data were analyzed using a linear mixed-effects model. Pairwise comparisons with Holm-Bonferroni correction were conducted with Hedge's g effect size to determine the magnitude of the difference. There was a main effect of intensity, exercise modality, and intensity * exercise modality interaction on both ESS (
< 0.001). Treadmill at a high intensity yielded the greatest ESS when compared to the other exercise modalities and intensities, while Bench Press and Biceps curls yielded the least ESS. All exercise intensities across all modalities resulted in turbulent blood flow. Clinicians must take into consideration how different exercise modalities and intensities affect ESS and Re of the carotid artery.
The purpose of this study was to determining the range of aerobic exercise on a treadmill for male Wistar rats at different ages. Twelve male Wistar rats were divide in three groups of immature, ...adults, and old (n= 4 in each). At first session, the rats began to run at a rate of 2 m/min to perform the fatigue test, and the treadmill speed was increased by 2 m/min every 2 minutes. This process of acceleration continued until the rats were no longer able to continue moving on the treadmill and became exhausted. Then, blood lactate of each subject measured immediately and their maximum speed was recorded. After 48 hours of recovery, animal performed maximum recorded speed on a treadmill in three 10-minute steps of 25%, 50% and 75%, respectively. Immediately after each percent blood lactate were measured and recorded. Immature rats at an average speed of 18 m/min were reached to their maximum speed with an average lactate concentration of 8±1.8 mmol/l. Adults rats at an average speed of 36 m/min were reached to their maximum speed with an average lactate concentration of 6.8±0.4 mmol/l. The old rats reached their maximum velocity with an average of 30 m/min with an average lactate concentration of 6.95±0.9 mmol/l. Therefore, it recommended that aerobic exercise in untrained rats start at a light speed, i.e. 25% of their maximum speed, which is lower than the lactate threshold, and gradually continue up to 50% of their maximum speed.
There is increasing attention to sprint interval exercise (SIE) training as a time-efficient exercise regime. Recent studies, including our own (Kujach et al., 2018), have shown that acute ...high-intensity intermittent exercise can improve cognitive function; however, the neurobiological mechanisms underlying the effect still remain unknown. We thus examined the effects of acute SIE on cognitive function by monitoring the peripheral levels of growth and neurotrophic factors as well as blood lactate (LA) as potential mechanisms. Thirty-six young males participated in the current study and were divided into two groups: SIE (
= 20; mean age: 21.0 ± 0.9 years) and resting control (CTR) (
= 16; mean age: 21.7 ± 1.3 years). The SIE session consisted of 5 min of warm-up exercise and six sets of 30 s of all-out cycling exercise followed by 4.5 min of rest on a cycling-ergometer. Blood samples to evaluate the changes of serum concentrations of brain-derived neurotrophic factor (BDNF), insulin-like growth factor-1 (IGF-1), vascular endothelial growth factor (VEGF), and blood LA were obtained at three time points: before, immediately after, and 60 min after each session. A Stroop task (ST) and trail making test (TMT) parts A and B were used to assess cognitive functions. Acute SIE shortened response times for both the ST and TMT A and B. Meanwhile, the peripheral levels of BDNF, IGF-1, and VEGF were significantly increased after an acute bout of SIE compared to those in CTR. In response to acute SIE, blood LA levels significantly increased and correlated with increased levels of BDNF, IGF-1, and VEGF. Furthermore, cognitive function and BDNF are found to be correlated. The current results suggest that SIE could have beneficial effects on cognitive functions with increased neuroprotective factors along with peripheral LA concentration in humans.
Purpose:
The objective of this study was to investigate metabolic energy contributions during high-intensity hatha yoga (HIHY) and to compare changes in physiological variables between active and ...passive recovery methods.
Methods:
The study involved 20 women yoga instructors (
n
= 20) who performed 10 min of HIHY (vigorous sun salutation). Upon completion, they were randomly assigned to either active (walking;
n
= 10) or passive (
savasana
;
n
= 10) recovery groups for a period of 10 min. During HIHY, physiological variables such as heart rate (HR
peak
and HR
mean
), oxygen uptake (VO
2peak
and VO
2mean
), and blood lactate concentrations (peak La
−
) were measured. Energetic contributions (phosphagen; W
PCR
, glycolytic; W
Gly
, and oxidative; W
Oxi
) in kJ and % were estimated using VO
2
and La
−
data. Furthermore, the metabolic equivalents (METs) of VO
2peak
and VO
2mean
were calculated. To compare different recovery modes, HR
post
, ΔHR, VO
2post
, ΔVO
2
, recovery La
−
, and recovery ΔLa
−
were analyzed.
Results:
The results revealed that HR
peak
, VO
2peak
, and peak La
−
during HIHY showed no differences between the two groups (
p
> 0.05). Values of HR
peak
, HR
mean
, METs of VO
2peak
and VO
2mean
, and La
−
during HIHY were 95.6% of HR
max
, 88.7% of HR
max
, 10.54 ± 1.18, 8.67 ±.98 METs, and 8.31 ± 2.18 mmol·L
−1
, respectively. Furthermore, W
Oxi
was significantly higher compared with W
PCR
, W
Gly
, and anaerobic contribution (W
PCR
+ W
Gly
), in kJ and % (
p
< 0.0001). VO
2post
and recovery ΔLa
−
were significantly higher in the active recovery group (
p
< 0.0001,
p
= 0.0369, respectively). Values of ΔVO
2
and recovery La
−
were significantly lower in the active group compared with the passive group (
p
= 0.0115,
p
= 0.0291, respectively).
Conclusions:
The study concluded that high-intensity hatha yoga which was performed for 10 min is a suitable option for relatively healthy people in the modern workplace who may have hatha yoga experience but do not have time to perform a prolonged exercise. Following active recovery, they can participate in further HIHY sessions during short breaks. Furthermore, a faster return to work can be supported by physiological recovery.
Purpose: This study compared physiological and perceptual variables between short and long durations of rowing-based high
intensity interval exercise (HIIE). Methods: Fourteen active adults (age = ...26.4 ± 7.2 yr) performed incremental rowing exercise to fatigue to measure maximal oxygen uptake (VO
2
max) and peak power output (PPO). The subsequent 20 min sessions required HIIE (eight 60 s efforts at 85%PPO with 90 s of active recovery at 20%PPO or 24 20 s efforts at 85%PPO with 30 s of active recovery at 20%PPO) or moderate intensity continuous exercise (MICE) at 40%PPO. During exercise, VO
2
, heart rate (HR), blood lactate concentration (BLa), rating of perceived exertion (RPE), and affective valence were measured. Results: Data show significantly (p < 0.001) higher peak VO
2
(84 ± 7 vs. 76 ± 5%VO
2
peak, d = 0.99), peak HR (94 ± 4%HRpeak vs. 90 ± 4%HRpeak, d = 1.12), BLa (7.0 ± 2.5 mM vs. 4.1 ± 1.0 mM, d = 1.22), end-exercise RPE (12.8 ± 2.0 vs. 11.0 ± 1.7, d = 1.29), and lower affective valence (2.1 ± 1.6 vs. 2.9 ± 1.2, d = 0.61) with long versus short HIIE. Time spent above 85%HRpeak was significantly higher (p < 0.001) in short versus long HIIE (606 ± 259 vs. 448 ± 26 s, d = 0.91). Conclusion: Longer rowing-based intervals elicit greater cardiometabolic and perceptual strain versus shorter efforts, making the latter preferable to optimize perceptual responses to HIIE.
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