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Although high and simulated altitude training has become an increasingly popular training method, no study has investigated the influence of acute hypoxic exposure on balance in team-sport athletes. Therefore, the purpose of this study was to investigate whether acute exposure to normobaric hypoxia is detrimental to balance performance in highly-trained basketball players. Nine elite and nine sub-elite male basketball players participated in a randomized, single-blinded, cross-over study. Subjects performed repeated trials of a single-leg balance test (SLBT) in an altitude chamber in normoxia (NOR; approximately sea level) with FiO2 20.9% and PiO2 ranging from 146.7 to 150.4 mmHg and in normobaric hypoxia (HYP; ~3,800 m above sea level) with FiO2 13.0% and PiO2 ranging from 90.9 to 94.6 mmHg. The SLBT was performed three times: 15 min after entering the environmental chamber in NOR or HYP, then two times more interspersed by 3-min rest. Peripheral oxygen saturation (SpO2) and heart rate (HR) were recorded at four time points: after the initial 15-min rest inside the chamber and immediately after each SLBT. Across the cohort, the balance performance was 7.1% better during NOR than HYP (P < 0.01, ηp2 = 0.58). However, the performance of the elite group was not impaired by HYP, whereas the sub-elite group performed worse in the HYP condition on both legs (DL: P = 0.02, d = 1.23; NDL: P = 0.01, d = 1.43). SpO2 was lower in HYP than NOR (P < 0.001, ηp2 = 0.99) with a significant decline over time during HYP. HR was higher in HYP than NOR (P = 0.04, ηp2 = 0.25) with a significant increase over time. Acute exposure to normobaric hypoxia detrimentally affected the balance performance in sub-elite but not elite basketball players.

(SaO2)To facilitate recovery from hypoxia, many freedivers use a breathing method called "hook breathing" (HB) after diving, involving an interrupted exhale to build up intrapulmonary pressure. Some divers experience a delay in recovery of arterial oxygen saturation (SaO2) after diving, interpreted as symptoms of mild pulmonary edema, and facilitated recovery may be especially important in this group to avoid hypoxic "blackout." We examined the influence of HB on recovery of (SaO2) in freedivers with slow recovery (SR) and fast recovery (FR) of (SaO2) after deep "free immersion" (FIM) apnea dives to 30 m depth. Twenty-two male freedivers, with a mean (SD) personal best in the discipline FIM of 57(26) m, performed two 30 m deep dives, one followed by HB and one using normal breathing (NB) during recovery, at different days and weighted order. (SaO2) and heart rate (HR) were measured via pulse oximetry during recovery. The SR group (n = 5) had a faster (SaO2) recovery using HB, while the FR group (n = 17) showed no difference between breathing techniques. At 105 s, the SR group reached a mean (SD) SaO(2) of 95(5)% using HB, while using NB, their (SaO2) was 87(5)% (p < 0.05), and 105-120 s after surfacing(SaO2) was higher with HB (p < 0.05). In SR subjects, the average time needed to reach 95% (SaO2) with HB was 60 s, while it was 120 s at NB (p < 0.05). HR was similar in the SR group, while it was initially elevated at HB in the FR group (p < 0.05). We conclude that HB efficiently increases (SaO2) recovery in SR individuals, but not in the FR group. The proposed mechanism is that increased pulmonary pressure with HB will reverse any pulmonary edema and facilitate oxygen uptake in divers with delayed recovery., Funding Agencies:Centro Superior de Estudios Universitarios La Salle (Madrid) Swedish Centre for Research in Sports (CIF) Mid Sweden University

Purpose: To determine whether heart-rate variability (HRV) was correlated with other training-load and training-tolerance markers for monitoring the effect of a training session on elite synchronized swimmers. Methods: The authors recorded the resting HRV of 12 elite swimmers (mean age = 21.5 [3.5] y) 3 times over 1 wk with a cadence of 48 h prior to the 2015 World Swimming Championships. They continuously monitored heart rate and obtained salivary cortisol (SC) samples before and after the last training session of the week. The authors measured capillary blood lactate (La) 2, 4, and 8 min after the last training session and monitored recovery HRV. They assessed rating of perceived exertion (RPE) over the entire session and tested the association between the highest La concentration (Lapeak), SC, and RPE and relative changes (Δ%) in the natural logarithm of the root-mean-square successive difference of intervals (LnRMSSD). The authors also calculated the smallest worthwhile change of the averaged pre and post LnRMSSD measurements. Results: There were periods of pronounced bradycardia (60.5 [16.7] beats/min) during training exercises corresponding to apneic exercise. The magnitude-based inferences showed nonclinically meaningful changes of LnRMSSD. Lapeak (6.8 [2.7] mmol/L) correlated positively with Δ%LnRMSSD and Δ%SC (r = .89, P = .001 and r = .61, P = .04, respectively). Conclusions: There was no change in LnRMSSD and Lapeak, Δ%SC, and RPE indicated reduced sympathetic activation and positive adaptation to the stress imposed by the session. Isolated HRV assessment may reveal a controversial interpretation of autonomic nervous system status or the training tolerance in elite synchronized swimming athletes due to the influence of the diving response.

BACKGROUND The purpose of this study was to determine the cardiorespiratory demands of standing and wheelchair (seated) fencing in a group of able-bodied fencers during simulated competitive bouts. METHODS Participants were ten male able-bodied fencers of regional level with previous training experience in wheelchair fencing. After a standardized warm-up, participants performed two series of simulated competitive epee bouts (5 and 15 touches) in a random order, either while standing or while sitting in a wheelchair. Expired gas was analyzed for oxygen consumption (VO2) and respiratory exchange ratio (RER) and heart rate were continually monitored. Energy expenditure (EE) was subsequently calculated. RESULTS VO2, HR and EE peak responses were greater during standing than seated fencing (P

The aim of the study is to compare the heart rate (HR) and rate of perceived exertion (RPE) responses as internal load indicators while performing duet routines during training and competition, both in the technical and free programs of synchronized swimming (SS). Participants were 10 SS Olympic medalists (age, 17.4 ± 3.0 years; height, 164.0 ± 6.1 cm; body mass, 52.0 ± 6.4 kg; training, 36.3 ± 6.2 h·wk; experience, 9.2 ± 2.6 years). They were monitored while performing the same technical duet or free duet, during a training session (T) and during an official competition (C). Heart rate was continuously monitored. Rate of perceived exertion was assessed using the Borg CR10 scale. Heart rate responses during T and C were almost identical: pre-exercise mean HR (b·min) was 130.5 ± 13.9 (T) and 133.6 ± 7.7 (C) and quickly increased yielding mean peak values of 184.8 ± 5.8 (T) and 184.8 ± 6.6 (C), with interspersed bradycardic events down to 86.6 ± 4 (T) and 86.3 ± 5 (C). Routines were perceived as "hard" to "extremely hard" by the swimmers in both conditions, and mean RPE scores (0-10+) were equally high during C (7.9 ± 1.2) and T (7.5 ± 1.2) (p = 0.223). Rate of perceived exertion inversely correlated with minimum (R = -0.545; p = 0.008) and mean HR (R = -0.452; p = 0.026) and positively correlated with HRrange (R = 0.520; p = 0.011). The internal load imposed by SS duets performed during training is virtually identical to that elicited in a real competitive situation. Therefore, practicing competitive routines is suitable for developing and maintaining the cardiovascular fitness that is needed for specific conditioning in elite synchronized swimmers, with the added value of favoring exercise automaticity, interindividual coordination, and artistic expression simultaneously.

This study examined the relationship between ratings of perceived exertion (RPE, CR-10), heart rate (HR), peak blood lactate (La peak), and immersion (IM) parameters in 17 elite synchronized swimmers performing 30 solo and duet routines during competition. All were video recorded (50 Hz) and an observational instrument was used to time the IM phases. Differences in the measured variables were tested using a linear mixed-effects model. RPE was 7.7 ± 1.1 and did not differ among routines, and neither did any of the HR parameters. There were differences among routines in La peak (F3,7=16.5; P=0.002), number of IM (F3,15=14.0; P0.001), total time immersed (F3,16=26.6; P0.001), percentage of time immersed (F3,13=6.5; P=0.007) and number of IM longer than 10 s (F3,19=3.0; P=0.04). RPE correlated positively to HR pre-activation, range of variation and recovery, IM parameters and La peak, and inversely to minimum and mean HR. A hierarchical multiple linear regression (MLR) model (number of IM10 s, HR recovery, minimum HR, and La peak) explained 62% RPE variance (adj. Rm 2=0.62; P0.001). A stepwise MLR model (La peak, mean IM time and pre-exercise HR) explained 46% of performance variance (adj. Rm 2=0.46; P0.001). Findings highlight the psycho-physical stress imposed by the combination of intense dynamic exercise with repeated and prolonged apnea intervals during SS events.

Purpose We aimed to characterize the cardiovascular, lactate and perceived exertion responses in relation to performance during competition in junior and senior elite synchronized swimmers. Methods 34 high level senior (21.4±3.6 years) and junior (15.9±1.0) synchronized swimmers were monitored while performing a total of 96 routines during an official national championship in the technical and free solo, duet and team competitive programs. Heart rate was continuously monitored. Peak blood lactate was obtained from serial capillary samples during recovery. Post-exercise rate of perceived exertion was assessed using the Borg CR-10 scale. Total competition scores were obtained from official records. Results Data collection was complete in 54 cases. Pre-exercise mean heart rate (beats·min−1) was 129.1±13.1, and quickly increased during the exercise to attain mean peak values of 191.7±8.7, with interspersed bradycardic events down to 88.8±28.5. Mean peak blood lactate (mmol·L−1) was highest in the free solo (8.5±1.8) and free duet (7.6±1.8) and lowest at the free team (6.2±1.9). Mean RPE (0–10+) was higher in juniors (7.8±0.9) than in seniors (7.1±1.4). Multivariate analysis revealed that heart rate before and minimum heart rate during the routine predicted 26% of variability in final total score. Conclusions Cardiovascular responses during competition are characterized by intense anticipatory pre-activation and rapidly developing tachycardia up to maximal levels with interspersed periods of marked bradycardia during the exercise bouts performed in apnea. Moderate blood lactate accumulation suggests an adaptive metabolic response as a result of the specific training adaptations attributed to influence of the diving response in synchronized swimmers. Competitive routines are perceived as very to extremely intense, particularly in the free solo and duets. The magnitude of anticipatory heart rate activation and bradycardic response appear to be related to performance variability.