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The aim of this study was to determine the effects of block training (BL) on pacing during a 20-km hilly cycling time trial (TT) in trained cyclists. Twenty male cyclists were separated into 2 groups: control and BL. The training of each cyclist was monitored during a period of 3 weeks. In the first week cyclists performed an overload period of 7 consecutive days of high-intensity interval training followed by 2 weeks of normal training. Cyclists performed 1 TT before intervention and 2 TT after 7 and 14 days at the end of training. Each training session consisted of 10 sets of 3 repeated maximal-effort sprints (15, 30, and 45 s) with an effort/recovery duration ratio of 1:5. The main finding of this study was that the power output displayed a significantly higher start from the start until the halfway point of the TT ( p < 0.05). Additionally, power output was characterized by a significant higher end spurt in the final 2 km in the BL after 2 weeks at the end of training ( p < 0.05). In addition, after 2 weeks at the end of the overload period the distribution of cadence was significantly lower throughout the TT ( p < 0.01). Therefore, a short period of consecutive days of intense training enhances cycling performance and changes the power output in the beginning and final part of the TT in trained cyclists. [ABSTRACT FROM AUTHOR]

To assess the validity of postexercise measurements in estimating peak oxygen uptake ( V̇O2peak) in swimming, we compared oxygen uptake ( V̇O2) measurements during supramaximal exercise with various commonly adopted methods, including a recently developed heart rate - V̇O2 modelling procedure. Thirty-one elite swimmers performed a 200-m maximal swim where V̇O2 was measured breath-by-breath using a portable gas analyzer connected to a respiratory snorkel, 1 min before, during, and 3 min postexercise. V̇O2peak(-20-0) was the average of the last 20 s of effort. The following postexercise measures were compared: ( i) first 20-s average ( V̇O2peak(0-20)); ( ii) linear backward extrapolation (BE) of the first 20 s (BE(20)), 30 s, and 3 × 20-, 4 × 20-, and 3 or 4 × 20-s averages; ( iii) semilogarithmic BE at 20 s (LOG(20)) and at the other same time intervals as in linear BE; and ( iv) predicted V̇O2peak using mathematical modelling ( p V̇O2(0-20)]. Repeated-measures ANOVA and post-hoc Bonferroni tests compared V̇O2peak (criterion) and each estimated value. Pearson's coefficient of determination ( r2) was used to assess correlation. Exercise V̇O2peak(-20-0) (mean ± SD 3531 ± 738 mL·min−1) was not different ( p > 0.30) from p V̇O2(0-20) (3571 ± 735 mL·min−1), BE(20) (3617 ± 708 mL·min−1), or LOG(20) (3627 ± 746 mL·min−1). p V̇O2(0-20) was very strongly correlated with exercise V̇O2peak ( r2 = 0.962; p < 0.001), and showed a low standard error of the estimate (146 mL·min−1, 4.1%) and the lowest mean difference (40 mL·min−1; 1.1%). We confirm that the new modelling procedure based on postexercise V̇O2 and heart rate measurements is a valid and accurate procedure for estimating V̇O2peak in swimmers and avoids the estimation bias produced by other methods. [ABSTRACT FROM AUTHOR]

Introduction: Resting heart (pulse) rate (RPR) monitoring may be a useful neurological assessment tool in chiropractic practice. Lower RPR generally reflects a better level of fitness and health status than higher RPR. However, the clinical significance of short-term changes in RPR remains unknown. The purpose of this study was to take an initial step towards understanding the clinical significance of short-term RPR changes, first, by describing short-term RPR changes between duplicated measurements, and second, by comparing RPR changes between groups with lower and higher baseline RPR. Methods: Seventy-three healthy adult volunteers received an RPR measurement on two days within a 1-week period. The mean difference between the two measurements (RPR change) in patients with lower versus higher baseline RPR was compared. Results: Mean RPR change in the low baseline group was -0.3 BPM (95% confidence interval [CI] = -2.7 to 2.1 BPM) whereas in the high baseline group, it was +4.4 BPM (95% CI = 1.2 to 7.6). This difference between groups was statistically significant (P = 0.02) with a large effect size (Cohen's d = 0.57). Conclusion: In this pilot study, a higher RPR at baseline was associated with increased RPR change, whereas a lower baseline RPR was associated with a stable or reduced RPR change. A future main study with a larger sample size and longer follow-up period is needed to better characterize both the natural variation of RPR over multiple repeated measurements, and the clinical significance of short-term RPR changes in terms of predicting longer-term health outcomes. [ABSTRACT FROM AUTHOR]

Many studies have researched the psychophysiological response and energy balance of athletes in numerous ultraendurance probes, but none has investigated an ultraendurance mountain running event. The current study aims to analyze changes in blood lactate concentration, rating of perceived exertion, heart rate, heart rate variability, and energy balance after the performance of an ultraendurance mountain running event. The parameters in the 6 participants who finished the event were analyzed (age, 30.8 ± 3.1 years; height, 176.2 ± 8.6 cm; body mass, 69.2 ± 3.7 kg). The race covered 54 km, with 6441 m of altitude change, 3556 m downhill and 2885 m uphill. The athletes completed together the race in 14 h and 6 min. After the ultraendurance event, the athletes presented a negative energy balance of 4732 kcal, a blood lactate concentration of 2.8 ± 0.3 mmol/L, a heart rate mean/heart rate maximum ratio of 0.64, a heart rate mean of 111.4 ± 5.9 beats/min, a decrease in vagal modulation, and an increase in sympathetic modulation, and recorded 19.5 ± 1.5 points on the 6-20 rating of perceived exertion scale. The event was a stressful stimulus for the athletes despite the low intensity measured by blood lactate concentration and heart rate. The results obtained may be used by coaches as a reference parameter of heart rate, heart rate variability, rating of perceived exertion, and lactate concentration to develop specific training programs. In addition, the energy balance data obtained in this research may improve nutritional intake strategies. [ABSTRACT FROM AUTHOR]

The aim of this study was to assess potential changes in the performance and cardiorespiratory responses of elite cross-country skiers following transition from the classic (CL) to the skating (SK) technique during a simulated skiathlon. Eight elite male skiers performed two 6 km (2 × 3 km) roller-skiing time trials on a treadmill at racing speed: one starting with the classic and switching to the skating technique (CL1-SK2) and another employing the skating technique throughout (SK1-SK2), with continuous monitoring of gas exchanges, heart rates, and kinematics (video). The overall performance times in the CL1-SK2 (21:12 ± 1:24) and SK1-SK2 (20:48 ± 2:00) trials were similar, and during the second section of each performance times and overall cardiopulmonary responses were also comparable. However, in comparison with SK1-SK2, the CL1-SK2 trial involved significantly higher increases in minute ventilation ( V̇E, 89.8 ± 26.8 vs. 106.8 ± 17.6 L·min−1) and oxygen uptake ( V̇O2; 3.1 ± 0.8 vs 3.5 ± 0.5 L·min−1) 2 min after the transition as well as longer time constants for V̇E, V̇O2, and heart rate during the first 3 min after the transition. This higher cardiopulmonary exertion was associated with ∼3% faster cycle rates. In conclusion, overall performance during the 2 time trials did not differ. The similar performance times during the second sections were achieved with comparable mean cardiopulmonary responses. However, the observation that during the initial 3-min post-transition following classic skiing cardiopulmonary responses and cycle rates were slightly higher supports the conclusion that an initial section of classic skiing exerts an impact on performance during a subsequent section of skate skiing. [ABSTRACT FROM AUTHOR]

Fencing is an Olympic sport in which athletes fight one against one using bladed weapons. Contests consist of three 3-min bouts, with rest intervals of 1 min between them. No studies investigating oxygen uptake and energetic demand during fencing competitions exist, thus energetic expenditure and demand in this sport remain speculative. The aim of this study was to understand the physiological capacities underlying fencing performance. Aerobic energy expenditure and the recruitment of lactic anaerobic metabolism were determined in 15 athletes (2 females and 13 males) during a simulation of fencing by using a portable gas analyzer (MedGraphics VO2000), which was able to provide data on oxygen uptake, carbon dioxide production and heart rate. Blood lactate was assessed by means of a portable lactate analyzer. Average group energetic expenditure during the simulation was (mean ± SD) 10.24 ± 0.65 kcal·min−1, corresponding to 8.6 ± 0.54 METs. Oxygen uptakeand heart rate were always below the level of anaerobic threshold previously assessed during the preliminary incremental test, while blood lactate reached its maximum value of 6.9 ± 2.1 mmol·L−1 during the final recovery minute between rounds. Present data suggest that physical demand in fencing is moderate for skilled fencers and that both aerobic energy metabolism and anaerobic lactic energy sources are moderately recruited. This should be considered by coaches when preparing training programs for athletes. [ABSTRACT FROM AUTHOR]

Introduction: One model for neurological assessment in chiropractic pertains to autonomic variability, tested commonly with heart rate variability (HRV). Since HRV may not be convenient to use on all patient visits, more user-friendly methods may help fill-in the gaps. Accordingly, this study tests the association between manual pulse rate and heart rate variability. The manual rates were also compared to the heart rate derived from HRV. Methods: Forty-eight chiropractic students were examined with heart rate variability (SDNN and mean heart rate) and two manual radial pulse rate measurements. Inclusion criteria consisted of participants being chiropractic students. Exclusion criteria for 46 of the participants consisted of a body mass index being greater than 30, age greater than 35, and history of: a) dizziness upon standing, b) treatment of psychiatric disorders, and c) diabetes. No exclusion criteria were applied to the remaining two participants who were also convenience sample volunteers. Linear associations between the manual pulse rate methods and the two heart rate variability measures (SDNN and mean heart) were tested with Pearson's correlation and simple linear regression. Results: Moderate strength inverse (expected) correlations were observed between both manual pulse rate methods and SDNN (r = -0.640, 95% CI -0.781, -0.435; r = -0.632, 95% CI -0.776, -0.425). Strong direct (expected) relationships were observed between the manual pulse rate methods and heart rate derived from HRV technology (r = 0.934, 95% CI 0.885, 0.962; r = 0.941, 95% CI 0.897, 0.966). Conclusion: Manual pulse rates may be a useful option for assessing autonomic variability. Furthermore, this study showed a strong relationship between manual pulse rates and heart rate derived from HRV technology. [ABSTRACT FROM AUTHOR]

Cardiac baroreflex gain is usually quantified as the reflex alteration in heart rate during changes in blood pressure without considering the effect of the rate of change in blood pressure on the estimated gain. This study sought to ( i) characterize baroreflex gain as a function of blood pressure oscillation frequencies using a repeat sit-to-stand method and ( ii) compare baroreflex gain values obtained using the sit-to-stand method against the modified Oxford method. Fifteen healthy individuals underwent the repeated sit-to-stand method in which blood pressure oscillations were driven at 0.03, 0.05, 0.07, and 0.1 Hz. Sixteen healthy participants underwent the sit-to-stand and modified Oxford methods to examine their agreement. Sit-to-stand baroreflex gain was highest at 0.05 Hz (8.8 ± 3.2 ms·mm Hg−1) and lowest at 0.1 Hz (5.8 ± 3.0 ms·mm Hg−1). Baroreflex gains at 0.03 Hz (7.7 ± 3.0 ms·mm Hg−1) and 0.07 Hz (7.5 ± 3.3 ms·mm Hg−1) were not different from the baroreflex gain at 0.05 Hz. There was moderate correlation between phenylephrine gain and sit-to-stand gain ( r values ranged from 0.52 to 0.75; all frequencies, p < 0.05), but no correlation between sodium nitroprusside gain and sit-to-stand gain ( r values ranged from -0.07 to 0.22; all p < 0.05). Bland-Altman analysis of phenylephrine gain and sit-to-stand gain showed poor agreement and a positive proportional bias. These results show that baroreflex gains derived from these 2 methods cannot be used interchangeably. Furthermore, cardiac baroreflex gain is frequency dependent between 0.03 Hz and 0.1 Hz, which challenges the conventional practice of summarizing baroreflex gain as a single number. [ABSTRACT FROM AUTHOR]

Decreased heart rate variability and attenuated heart rate recovery following exercise are associated with an increased risk of mortality in cardiac patients. This study investigated the effects of 12 weeks of moderate-intensity endurance exercise (END) and a novel low-volume high-intensity interval exercise protocol (HIT) on measures of heart rate recovery and heart rate variability in patients with coronary artery disease (CAD). Fourteen males with CAD participated in 12 weeks of END or HIT training, each consisting of 2 supervised exercise sessions per week. END consisted of 30-50 min of continuous cycling at 60% peak power output (PPO). HIT involved ten 1-min intervals at 88% PPO separated by 1-min intervals at 10% PPO. Heart rate recovery at 1 min and 2 min was measured before and after training (pre- and post-training, respectively) using a submaximal exercise bout. Resting time and spectral and nonlinear domain measures of heart rate variability were calculated. Following 12 weeks of END and HIT, there was no change in heart rate recovery at 1 min (END, 40 ± 12 beats·min−1 vs. 37 ± 19 beats·min−1; HIT, 31 ± 8 beats·min−1 vs. 35 ± 8 beats·min−1; p ≥ 0.05 for pre- vs. post-training) or 2 min (END, 44 ± 18 beats·min−1 vs. 43 ± 19 beats·min−1; HIT, 42 ± 10 beats·min−1 vs. 50 ± 6 beats·min−1; p ≥ 0.05 for pre- vs. post-training). All heart rate variability indices were unchanged following END and HIT training. In conclusion, neither END nor HIT exercise programs elicited training-induced improvements in cardiac autonomic function in patients with CAD. The absence of improvements with training may be attributed to the optimal medical management and normative pretraining state of our sample. [ABSTRACT FROM AUTHOR]