Dance Creativity Measures: A Reliability Study

Abstract

Recent research (Lee &; Weeks, 1987; Weeks, Lee, &; Elliott, 1987) investigating the processes responsible for the contextual interference phenomenon has used a modified short-term motor retention paradigm to support the reconstruction explanation (Lee &; Magill, 1985; Magill, 1989; Magill &; Hall, 1990). The present experiment was an extension of these experiments in which forgetting of an acquisition task was induced through performance of either a similar or dissimilar distractor task during the intertrial interval. The effects of an extra practice trial with the acquisition task as well as no activity during the intertrial interval were also investigated. In addition, forgetting of the acquisition task was assessed prior to a reconstruction trial, which immediately preceded a 2-min filled retention interval. Both similar and dissimilar distractor tasks caused equivalent amounts of forgetting of the acquisition task prior to the reconstruction trial. However, retention of the acquisition task was significantly improved if its reconstruction occurred following forgetting due to interference from performance of a similar distractor task. These findings suggest forgetting and subsequent reconstruction alone are not sufficient for improved retention. These processes must occur in the context of a similar task for improved retention.     

Postural control quantification in minimally and moderately impaired persons with multiple sclerosis: The reliability of a posturographic test and its relationships with functional ability

BackgroundPostural control has been associated with the functional impairment in persons with multiple sclerosis (pwMS). However, there is a need for reliable methods to assess postural control in early stages of the disease, when subtle changes can be difficult to detect. The aims of this study were to assess the absolute and relative reliability of a standing and a sitting posturographic protocol in minimally (Expanded Disability Status Scale ≤ 2) and moderately (2.5 ≤ Expanded Disability Status Scale ≤ 4) impaired pwMS, and to analyze relationships among postural control and functional mobility and gait performance.MethodsTo assess postural control in an upright stance, 14 minimally and 16 moderately impaired pwMS performed six 70 s trials in tandem stance, 3 with their weaker leg behind (TS_WL) and 3 with their stronger leg behind (TS_SL). Additionally, participants completed five 70 s trials using an unstable sitting protocol (US) to assess trunk stability. The mean radial errors of TS_WL, TS_SL, and US trials were calculated as postural control indexes. Furthermore, participants performed the Timed Up and Go test (TUG) and the Timed 25-foot Walk test (T25FW) to measure their functional mobility and gait speed, respectively. Reliability was evaluated using the intraclass correlation coefficient (ICC_3,1) and the standard error of measurement (SEM). Analyses of variances were carried out to assess between-group differences. Hedges’ g index (d_g) was used to estimate the effect size of differences. Pearson correlation analyses (r) were performed to examine the relationships among the postural control and the functional tests.ResultsPosturographic tests showed a high reliability in both minimally (0.87 ≤ ICC ≤ 0.92; 9.32% ≤ SEM ≤ 11.76%) and moderately (0.80 ≤ ICC ≤ 0.92; 10.33% ≤ SEM ≤ 15.33%) impaired pwMS. Similarly, T25FW and TUG displayed a high consistency in minimally (0.89 ≤ ICC ≤ 0.94; 3.43% ≤ SEM ≤ 5.17%) and moderately (0.85 ≤ ICC ≤ 0.93; 5.57% ≤ SEM ≤ 6.56%) impaired individuals. Minimally impaired pwMS showed a better performance on the TUG, T25FW, and TS_WL than moderately impaired individuals (p < 0.05; d_g ≥ 0.8). The TS_WL, TS_SL, and US variables correlated with TUG scores (0.419 ≤ r ≤ 0.604; p < 0.05), but TS_WL also correlated with T25FW scores (r = 0.53; p < 0.01). Furthermore, US scores correlated with both tandem stance parameters (TS_WL: r = 0.54, p < 0.01; TS_SL: r = 0.43, p < 0.05).ConclusionTandem and sitting posturographic tests provide reliable measures of postural control in pwMS, even in individuals with a homogeneous disease profile. Gait speed, functional mobility, and weaker leg status seem decisive in assessing the degree of physical activity limitation in pwMS. Finally, although trunk stability does not seem to be so affected by the course of the disease, it remains relevant for postural control and functional capacity.     

Markers of isometric training intensity and reductions in resting blood pressure

Abstract

In this study, we examined the correlations between selected markers of isometric training intensity and subsequent reductions in resting blood pressure. Thirteen participants performed a discontinuous incremental isometric exercise test to volitional exhaustion at which point mean torque for the final 2-min stage (2min-torque_peak) and peak heart rate peak (HR_peak) were identified. Also, during 4 weeks of training (3 sessions per week, comprising 4 × 2 min bilateral leg isometric exercise at 95% HR_peak), heart rate (HR_train), torque (Torque_train), and changes in EMG amplitude (ΔEMG_amp) and frequency (ΔEMG_freq) were determined. The markers of training intensity were: Torque_train relative to the 2min-torque_peak (%2min-torque_peak), EMG relative to EMG_peak (%EMG_peak), HR_train ΔEMG_amp, ΔEMG_freq, and %MVC. Mean systolic (?4.9 mmHg) and arterial blood pressure (?2.7mmHg) reductions correlated with %2min-torque_peak (r = ?0.65, P = 0.02 and r = ?0.59, P = 0.03), ΔEMG_amp (r = 0.66, P = 0.01 and r = 0.59, P = 0.03), ΔEMG_freq (r = ?0.67, P = 0.01 and r = ?0.64, P = 0.02), and %EMG_peak (systolic blood pressure only; r = ?0.63, P = 0.02). These markers best reflect the association between isometric training intensity and reduction in resting blood pressure observed after bilateral leg isometric exercise training.     

Validity and reliability of the Moxy oxygen monitor during incremental cycling exercise

Introduction: The Moxy is a novel, cutaneously placed muscle oxygen monitor which claims to measure local oxygen saturation (SmO₂) and total haemoglobin (THb) using near-infrared spectroscopy. If shown to be reliable, its data storage and telemetric capability will be useful for assessing localised O₂ usage during field-based exercise. This study investigated the reliability of the Moxy during cycling and assessed the correlations between its measurements, whole-body O₂ consumption (VO₂) and heart rate (HR). Methods: Ten highly trained cyclists performed an incremental, step-wise cycling protocol on two occasions while wearing the Moxy. SmO₂, THb, VO₂ and HR were recorded in the final minute of each five-minute stage. Data were analysed using Spearman’s Order-Rank Coefficient (SROC), Intraclass Correlation (ICC), and Coefficient of Variance (COV). Significance was set at p?≤?.05. Results: SmO₂ showed a ‘strong’ or ‘very large’ correlation between trials (SROC: r?=?0.842–0.993, ICC: r?=?0.773–0.992, p?≤?.01) and was moderately correlated with VO₂ and HR (r?=??0.71–0.73, p?≤?.01). SmO₂ showed a moderate to high reliability at low intensities, but this decreased as relative exercise intensity increased. THb showed poor correlations between tests and with the other measured variables, but was highly reliable at all power outputs. Conclusions: The Moxy is a reliable device to measure SmO₂ at low to moderate intensities, but at higher intensities, greater variation in measurements occurs, likely due to tissue ischaemia or increased movement artefacts due to more frequent muscular contractions. THb has low variation during exercise, and does not appear to be a valid indicator of muscle oxygenation.     

Isolated Obesity Is Not Enough to Impair Cardiac Autonomic Modulation in Metabolically Healthy Men

Purpose: To evaluate whether excess body mass influences the heart rate variability (HRV) indexes at rest, and to correlate adiposity indicators and the aerobic fitness with cardiac autonomic variables in metabolically healthy young adults. Method: In all, 41 untrained males (M_age = 21.80, SD = 2.14 years), 14 normal weight (M_BMI = 22.28, SD = 1.86 kg?m^?2), 11 overweight (M_BMI = 26.95, SD = 1.43 kg?m^?2), and 16 obese (M_BMI = 33.58, SD = 3.06 kg?m^?2) metabolically healthy (normal values of blood pressure, fasting blood glucose, triglycerides, and total cholesterol), underwent evaluations of the HRV at rest and of the peak oxygen consumption (VO₂ peak) during maximal exercise on a cycle ergometer. Results: Blood pressure, heart rate, HRV indexes, casual blood glucose, oxidative stress, and antioxidant activity did not differ among the groups. The VO₂ peak (mL?kg^?1?min^?1) was lower in the obese group compared with the normal weight and overweight groups. The body mass (r = ?.40 to ?.45) and abdominal circumference (r = ?.39 to ?.52) were slightly to moderately correlated with SD1, SD2, RMSSD, SDNN, pNN50, LF, and HF indexes and total power. The VO₂ peak (mL?kg^?1?min^?1) was slightly to moderately correlated (r = .48 to .51) with SD2, SDNN, and LF indexes in the individuals with excess body mass. Conclusion: Cardiac autonomic modulation at rest was preserved in metabolically healthy obese young men. However, the indicators of adiposity, as well as the aerobic fitness were correlated with cardiac autonomic modulation in the individuals with excess body mass.     

Comparison of maximal anaerobic running tests on a treadmill and track

Abstract

To develop a track version of the maximal anaerobic running test, 10 sprint runners and 12 distance runners performed the test on a treadmill and on a track. The treadmill test consisted of incremental 20-s runs with a 100-s recovery between the runs. On the track, 20-s runs were replaced by 150-m runs. To determine the blood lactate versus running velocity curve, fingertip blood samples were taken for analysis of blood lactate concentration at rest and after each run. For both the treadmill and track protocols, maximal running velocity (v _max), the velocities associated with blood lactate concentrations of 10 mmol · l^?1 ( v _10 mM) and 5 mmol · l^?1 ( v _5 mM), and the peak blood lactate concentration were determined. The results of both protocols were compared with the seasonal best 400-m runs for the sprint runners and seasonal best 1000-m time-trials for the distance runners. Maximal running velocity was significantly higher on the track (7.57 ± 0.79 m · s^?1) than on the treadmill (7.13 ± 0.75 m · s^?1), and sprint runners had significantly higher v _max, v _10 mM, and peak blood lactate concentration than distance runners (P<0.05). The Pearson product – moment correlation coefficients between the variables for the track and treadmill protocols were 0.96 (v _max), 0.82 (v _10 mM), 0.70 (v _5 mM), and 0.78 (peak blood lactate concentration) (P<0.05). In sprint runners, the velocity of the seasonal best 400-m run correlated positively with v _max in the treadmill (r = 0.90, P<0.001) and track protocols (r = 0.92, P<0.001). In distance runners, a positive correlation was observed between the velocity of the 1000-m time-trial and v _max in the treadmill (r = 0.70, P<0.01) and track protocols (r = 0.63, P<0.05). It is apparent that the results from the track protocol are related to, and in agreement with, the results of the treadmill protocol. In conclusion, the track version of the maximal anaerobic running test is a valid means of measuring different determinants of sprint running performance.     

The effects of work:rest duration on physiological and perceptual responses during intermittent exercise and performance

Abstract

In this study, we examined the effects of different work:rest durations during 20 min intermittent treadmill running and subsequent performance. Nine males (mean age 25.8 years, s = 6.8; body mass 73.9 kg, s = 8.8; stature 1.75 m, s = 0.05; [Vdot]O_2max 55.5 ml · kg^?1 · min^?1, s = 5.8) undertook repeated sprints at 120% of the speed at which [Vdot]O_2max was attained interspersed with passive recovery. The work:rest ratio was constant (1:1.5) with trials involving either short (6:9 s) or long (24:36 s) work:rest exercise protocols (total exercise time 8 min). Each trial was followed by a performance run to volitional exhaustion at the same running speed. Testing order was randomized and counterbalanced. Heart rate, oxygen consumption, respiratory exchange ratio, and blood glucose were similar between trials (P > 0.05). Blood lactate concentration was greater during the long than the short exercise protocol (P < 0.05), whereas blood pH was lower during the long than the short exercise protocol (7.28, s = 0.11 and 7.30, s = 0.03 at 20 min, respectively; P < 0.05). Perceptions of effort were greater throughout exercise for the long than the short exercise protocol (16.6, s = 1.4 and 15.1, s = 1.6 at 20 min, respectively; P < 0.05) and correlated with blood lactate (r = 0.43) and bicarbonate concentrations (r = ?0.59; P < 0.05). Although blood lactate concentration at 20 min was related to performance time (r = ?0.56; P < 0.05), no differences were observed between trials for time to exhaustion (short exercise protocol: 95.8 s, s = 30.0; long exercise protocol: 92.0 s, s = 37.1) or physiological responses at exhaustion (P > 0.05). Our results demonstrate that 20 min of intermittent exercise involving a long work:rest duration elicits greater metabolic and perceptual strain than intermittent exercise undertaken with a short work:rest duration but does not affect subsequent run time to exhaustion.     

The Influence of Exercise Intensity on Postexercise Baroreflex Sensitivity

Purpose: The purpose of this study was to investigate the influence of exercise intensity on postexercise supine and tilt baroreflex sensitivity (BRS). Method: Nine healthy, active men performed 2 conditions of interval cycling of 40% maximal work rate (WR_max) and 75% WR_max of matched work done and a control condition of no exercise in a counterbalanced order. BRS outcome measures were determined at preexercise and postexercise up to +24 hr in supine and tilt positions. R-R interval and blood pressure data were collected over consecutive 10-min periods and were analyzed by Fast Fourier transformation analysis. Results: A fully repeated analysis of variance revealed a significant interaction (p < .05) between time and condition in supine for BRS_αLF, F(3, 134) = 5.19, p < .05, ES = .39, and BRS_TFTG, F(3, 134) = 5.65, p < .05, ES = .41, and in tilt for BRS_UpUp, F(3, 134) = 3.54, p < .05, ES = .31, BRS_DownDown, F(3, 134) = 5.94, p < .05, ES = .43, BRS_αLF, F(4, 134) = 6.23, p < .05, ES = .44, and BRS_TFTG, F(4, 134) = 9.22, p < .05, ES = .54. There were significant differences (p < .05) between condition comparisons at +15 min and between control and 75% WR_max and between the 40% WR_max and 75% WR_max conditions at +60 min. At +15 min, BRS was lower in the 75% WR_max condition compared with the 40% WR_max condition and the control condition, and it was lower in the 40% WR_max condition than in the control condition. Conclusion: The findings demonstrate an intensity-dependent relationship in the BRS response following exercise.     

Validity of a Tympanic Thermometer and Thermal Imaging Camera for Measuring Core and Skin Temperature during Exercise in the Heat

ABSTRACT

This study compared criterion to minimally invasive, practical measures of core (T_c) and skin (T_sk) temperature during 30 min of moderate-intensity cycle exercise in a heat chamber (35°C, 60% rH). T_c was monitored using a core temperature pill (T_c(Pill)) and tympanic thermometer (T_c(Tymp)) during rest, exercise, and recovery in 15 participants. T_sk was monitored using hard-wired skin thermistors attached to a data logger (T_sk(T)) and a thermal imaging camera (T_sk(IR)) in 11 participants. T_c measurement resulted in no significant difference (p > 0.05), a mean bias of 0.1°C, coefficient of variation (CV%) of 1.0%, and correlation of r = 0.74 between devices. T_sk measurement resulted in a significant difference (p = 0.01), a mean bias of 0.6°C, CV% of 2.3%, and correlation of r = 0.61 between devices. T_c(Tymp) demonstrated acceptable agreement with T_c(Pill); however, caution is advised when using T_sk(IR) to give accurate measures of T_sk during exercise.     

The influence of 2 weeks of low-volume high-intensity interval training on health outcomes in adolescent boys

Abstract

The present study aimed to establish whether 2 weeks of high-intensity interval training would have a beneficial effect on aerobic fitness, fat oxidation, blood pressure and body mass index (BMI) in healthy adolescent boys. Ten adolescent boys (15.1 ± 0.3 years, 1.3 ± 0.2 years post-estimated peak height velocity) completed six sessions of Wingate-style high-intensity interval training over a 2-week period. The first session consisted of four sprints with training progressed to seven sprints in the final session. High-intensity interval training had a beneficial effect on maximal O₂ uptake (mean change, ±90% confidence intervals: 0.19 L · min^?1, ±0.19, respectively), on the O₂ uptake at the gas exchange threshold (0.09 L · min^?1, ±0.13) and on the O₂ cost of sub-maximal exercise (–0.04 L · min^?1, ±0.04). A beneficial effect on the contribution of lipid (0.06 g · min^?1, ±0.06) and carbohydrate (–0.23 g · min^?1, ±0.14) oxidation was observed during sub-maximal exercise, but not for the maximal rate of fat oxidation (0.04 g · min^?1, ±0.08). Systolic blood pressure (1 mmHg, ±4) and BMI (0.1 kg · m², ±0.1) were not altered following training. These data demonstrate that meaningful changes in health outcomes are possible in healthy adolescent boys after just six sessions of high-intensity interval training over a 2-week period.     

Risk of bias and reporting practices in studies comparing VO2max responses to sprint interval vs. continuous training: A systematic review and meta-analysis

Background:It remains unclear whether studies comparing maximal oxygen uptake(VO_{2 max}) response to sprint interval training(SIT) vs.moderate-intensity continuous training(MICT) are associated with a high risk of bias and poor reporting quality.The purpose of this study was to evaluate the risk of bias and quality of reporting in studies comparing changes in VO_{2 max} between SIT and MICT.Methods:We conducted a comprehensive literature search of 4 major databases:AMED,CINAHL,E...     

Critical velocity: A predictor of 2000-m rowing ergometer performance in NCAA D1 female collegiate rowers

Abstract

The aims of this study were to examine the use of the critical velocity test as a means of predicting 2000-m rowing ergometer performance in female collegiate rowers, and to study the relationship of selected physiological variables on performance times. Thirty-five female collegiate rowers (mean ± s: age 19.3 ± 1.3 years; height 1.70 ± 0.06 m; weight 69.5 ± 7.2 kg) volunteered to participate in the study. Rowers were divided into two categories based on rowing experience: varsity (more than 1 year collegiate experience) and novice (less than 1 year collegiate experience). All rowers performed two continuous graded maximal oxygen consumption tests (familiarization and baseline) to establish maximal oxygen uptake ([Vdot]O_2max), peak power output, and power output at ventilatory threshold. Rowers then completed a critical velocity test, consisting of four time-trials at various distances (400 m, 600 m, 800 m, and 1000 m) on two separate days, with 15 min rest between trials. Following the critical velocity test, rowers completed a 2000-m time-trial. Absolute [Vdot]O_2max was the strongest predictor of 2000-m performance (r = 0.923) in varsity rowers, with significant correlations also observed for peak power output and critical velocity (r = 0.866 and r = 0.856, respectively). In contrast, critical velocity was the strongest predictor of 2000-m performance in novice rowers (r = 0.733), explaining 54% of the variability in performance. These findings suggest the critical velocity test may be more appropriate for evaluating performance in novice rowers.     

Feasibility of the two-point method for assessing the force-velocity relationship during lower-body and upper-body isokinetic tests

ABSTRACT

This study aimed to (1) evaluate the shape of the force-velocity (F-V) relationship obtained from different muscles, (2) explore the concurrent validity of the two-point method with respect to the multiple-point method, (3) evaluate whether the F-V relationship can discriminate between muscle groups and genders, and (4) explore the generalisability of the same F-V relationship parameters (maximal force [F₀], maximal velocity [V₀]), and maximal power [P₀]) between different tasks. The F-V relationship of 22 physically active participants (12 women) were tested during knee extension, knee flexion, elbow extension and elbow flexion through the multiple- (eight velocities: 30-60-90-120-150-180-210-240º/s) and two-point (two velocities: 60–180º/s) methods. The findings revealed (1) highly linear F-V relationships (r ≥ 0.893), (2) high concurrent validity of the two-point method for F₀, but lower for V₀ and P₀, (3) the outcomes of both methods were sensitive to the muscle groups (higher for knee muscles) and gender (higher for men), and (4) the magnitude of the same F-V parameters were poorly correlated between different tasks (median r < 0.1). These results support the two-point method as a valid and sensitive procedure for determining the maximal capacities of the muscles to produce F, but not V, during isokinetic tests.     

Scaling isometric mid-thigh pull maximum strength in division I Athletes: are we meeting the assumptions?

ABSTRACT

This study examined the validity of various scaling methods, isometric mid-thigh pull (IMTP) peak force using various scaling methods, and the relationships between IMTP peak force and countermovement jump height. Fifty-one collegiate baseball and soccer athletes performed two maximal IMTPs. Absolute peak force was compared between teams and when data were scaled using ratio (RS), traditional allometric (ALLO_Trad), and fitted allometric (ALLO_Fit) scaling. ALLO_Trad and ALLO_Fit validity was violated because different derived exponents existed for baseball (b = 0.20) and soccer (b = 1.20). Soccer athletes produced greater RS peak force compared to baseball (p = 0.012), while no difference existed with absolute, ALLO_Trad or ALLO_Fit (all p > 0.05) peak force. Moderate relationships existed between body mass and absolute (r = 0.402, p = 0.003) and RS (r = -0.328, p = 0.019) peak force, while trivial relationships existed with ALLO_Trad and ALLO_Fit (both r < -0.10, p > 0.05). Trivial relationships existed between countermovement jump height and absolute, RS, ALLO_Trad, and ALLO_Fit (all r < 0.20, p > 0.05) peak force. The current dataset violated allometric scaling assumptions, making it inappropriate to use ALLO_Trad and ALLO_Fit scaling. Practitioners must understand the assumptions, limitations, and purpose of scaling methods.     

Muscle Fiber Type Composition and Knee Extension Isometric Strength Fatigue Patterns in Power- and Endurance-Trained Males

Abstract

Muscle fiber type composition in the vastus lateralis and knee extension isometric strength fatigue patterns were assessed in eight endurance-trained and eight power-trained males. Two different 25-trial isometric contraction exercise regimens were administered: a 10-second contraction, 5-second intertrial rest condition designed to induce a fast rate of fatigue and a 10-second contraction, 20-second intertrial rest condition designed to induce a slower rate of fatigue. The power group fatigued almost four times faster than the endurance group in the 10:5 exercise condition. In the 10:20 exercise condition, the endurance group showed no fatigue pattern while the power group had a significant strength decrement of 32%. In both exercise conditions, the power group exhibited more complex fatigue patterns in terms of statistically significant trend components. Maximum isometric strength correlated positively with slow twitch (ST) percent number in power (r = .80) and endurance (r = .48) groups, but negatively with linear trend coefficients in endurance (r = -.62) and power (r = -.80) groups. Maximum isometric strength also correlated higher with fatigue curve trend coefficients than did muscle fiber type composition. Thus, a faster rate of fatigue was associated with higher maximum isometric strength and with higher ST percent number and area. Since maximum isometric strength correlated with body weight (r = .86 for groups combined), both maximum isometric strength and muscle mass appear to be more important determinants of knee extension isometric strength fatigue patterns than muscle fiber type composition.     

Twelve weeks of low volume sprint interval training improves cardio-metabolic health outcomes in overweight females

This study compared the effects of 12-week sprint interval training (SIT), high-intensity interval training (HIIT), and moderate-intensity continuous training (MICT) on cardiorespiratory fitness (V?O_2peak), body mass and insulin sensitivity in overweight females. Forty-two overweight women (age 21.2 ± 1.4 years, BMI 26.3 ± 2.5 kg·m^?2) were randomized to the groups of SIT (80 × 6-s sprints + 9-s rest), and isoenergetic (300KJ) HIIT (~9 × 4-min cycling at 90% V?O_2peak + 3-min rest) and MICT (cycling at 60% V?O_2peak for ~ 61-min). Training intervention was performed 3 d·week^?1 for 12 weeks. After intervention, all three groups induced the same improvement in V?O_2peak (~ +25%, p < 0.001) and a similar reduction in body mass (~ – 5%, p < 0.001). Insulin sensitivity and fasting insulin levels were improved significantly on post-training measures in SIT and HIIT by ~26% and ~39% (p < 0.01), respectively, but remain unchanged in MICT. In contrast, fasting glucose levels were only reduced with MICT (p < 0.01). The three training strategies are equally effective in improving V?O_2peak and reducing body mass, however, the SIT is time-efficient. High-intensity training (i.e. SIT and HIIT) seems to be more beneficial than MICT in improving insulin sensitivity.

Abbreviations: BMI: body mass index; CVD: cardiovascular disease; HIEG: hyperinsulinaemic euglycaemic glucose; HIIT: high-intensity interval training; HOMA-IR: homeostasis model assessment of insulin resistance; HR: heart rate; MICT: moderate-intensity continuous training; RPE: ratings of perceived exertion; SIT: sprint interval training; T2D: type 2 diabetes; V?O_2peak: peak oxygen consumption     

Long-term exposure to fine particulate matter modifies the association between physical activity and hypertension incidence

BackgroundThe trade-off between the benefits of regular physical activity (PA) and the potentially detrimental effects of augmented exposure to air pollution in highly polluted regions remains unclear. This study aimed to examine whether ambient fine particulate matter (PM_2.5) exposure modified the impacts of PA volume and intensity on hypertension risk.MethodsWe included 54,797 participants without hypertension at baseline in a nationwide cohort of the Prediction for Atherosclerotic Cardiovascular Disease Risk in China (China-PAR) project. PA volume and intensity were assessed by questionnaire, and high-resolution (1 km ×1 km) PM_2.5 estimates were generated using a satellite-based model.ResultsDuring 413,516 person-years of follow-up, 12,100 incident hypertension cases were identified. PM_2.5 significantly modified the relationship between PA and hypertension incidence (p_interaction < 0.001). Increased PA volume was negatively associated with incident hypertension in the low PM_2.5 stratum (<59.8 μg/m³, p_trend < 0.001), with a hazard ratio of 0.81 (95% confidence interval (95%CI): 0.74–0.88) when comparing the fourth with the first quartile of PA volume. However, the health benefits were not observed in the high PM_2.5 stratum (≥59.8 μg/m³, p_trend = 0.370). Moreover, compared with light PA intensity, vigorous intensity was related to a 20% (95%CI: 9%–29%) decreased risk of hypertension for participants exposed to low PM_2.5, but a 17% (95%CI: 4%–33%) increased risk for those with high PM_2.5 levels.ConclusionPA was associated with a reduced risk of hypertension only among participants with low PM_2.5 exposure. Our findings recommended regular PA to prevent hypertension in less polluted regions and reinforced the importance of air quality improvement.     

Assessment of Differing Definitions of Accelerometer Nonwear Time

Abstract

Twelve college and high school varsity male swimmers swam 200 yd. for time once a day for 16 days following the ingestion of a large meal (673 g). Each subject performed under rotating experimental conditions, which involved a post-meal rest interval of ½ hr., 1 hr., 2 hr., or no eating for at least 3 hr. before swimming. A nonsignificant F of .53 was obtained when the data were subjected to a single-factor with repeated measures analysis of variance.

It was concluded that swimming performance time was not affected by the time interval between eating and swimming. No stomach cramps were reported; most cases of stomach nausea occurred in the ½-hr. interval group, and scattered minor physical disturbances occurred under the other conditions.     

Reliability of NIRS portable device for measuring intercostal muscles oxygenation during exercise

ABSTRACT

This study assessed the intra-individual reliability of oxygen saturation in intercostal muscles (SmO₂-m.intercostales) during an incremental maximal treadmill exercise by using portable NIRS devices in a test-retest study. Fifteen marathon runners (age, 24.9 ± 2.0 years; body mass index, 21.6 ± 2.3 kg·m^?2; V?O₂-peak, 63.7 ± 5.9 mL·kg^?1·min^?1) were tested on two separate days, with a 7-day interval between the two measurements. Oxygen consumption (V?O₂) was assessed using the breath-by-breath method during the V?O₂-test, while SmO₂ was determined using a portable commercial device, based in the near-infrared spectroscopy (NIRS) principle. The minute ventilation (VE), respiratory rate (RR), and tidal volume (Vt) were also monitored during the cardiopulmonary exercise test. For the SmO₂-m.intercostales, the intraclass correlation coefficient (ICC) at rest, first (VT1) and second ventilatory (VT2) thresholds, and maximal stages were 0.90, 0.84, 0.92, and 0.93, respectively; the confidence intervals ranged from ?10.8% – +9.5% to ?15.3% – +12.5%. The reliability was good at low intensity (rest and VT1) and excellent at high intensity (VT2 and max). The Spearman correlation test revealed (p ≤ 0.001) an inverse association of SmO₂-m.intercostales with V?O₂ (ρ = ?0.64), VE (ρ = ?0.73), RR (ρ = ?0.70), and Vt (ρ = ?0.63). The relationship with the ventilatory variables showed that increased breathing effort during exercise could be registered adequately using a NIRS portable device.     

One-year endurance training: Effects on lung function and airway inflammation

Abstract

The aim of this study was to determine whether endurance training in athletes induces airway inflammation and pulmonary function disorders. Respiratory pattern and function were analysed in ten healthy endurance runners at rest, during sub-maximal exercise, and during the recovery. Inflammatory cells and metabolites (histamine, interleukin-8, and leukotriene E₄) were measured in sputum at rest and after exercise. The experiments were conducted on three different occasions (basic endurance training, pre-competitive and competitive periods). In spite of the absence of post-exercise spirometric changes and respiratory symptoms, airway cells counts and inflammatory markers changed significantly. At the beginning of the experiment, athletes' induced sputum showed an abundance of macrophages compared with neutrophils. We found a high percentage of neutrophils during the pre-competitive and competitive periods of the sport season (41% and 37%), a significant increase in macrophage counts during the pre-competitive period (51%), and a significant rise in total cells, interleukin-8, leukotriene E₄, and histamine during the competitive period. In conclusion, one year's training increased markers of inflammation in the airways of endurance runners without symptoms or changes in pulmonary function, suggesting that airway inflammation is of insufficient magnitude to markedly impact lung function in healthy athletes.