Predictors of Performance during a 161 km Mountain Footrace

Training volume and cardiovascular dynamics influence endurance performance. However, there is limited information on the interplay between training volume, cardiovascular dynamics, and performance in ultra-marathon athletes. PURPOSE: We aimed to determine predictors of performance in finishers of the 2023 Western States Endurance Run (WSER). METHODS: Sixty participants who finished the race (49 males/11 females; mean age: 44.7 ± 9.6 y, range: 26–66 y; BMI: 22.7 ± 2.2 kg/m2) completed pre-race surveys including average training volume (AV) and peak training volume (PV), as well as resting cardiovascular measures including resting heart rate (RHR) and augmentation index (AIx), a measure of wave reflection characteristics. Based on WSER completion time, we calculated average running velocity (RV). We assessed associations among 22 variables using bivariate correlation analysis (Pearson’s Correlation for normally distributed data and Spearman’s Rank Correlation if normality was not met). Within our listed variables, normality was met in age and AV. Additionally, we completed multiple regression analyses for predictors. We present descriptive data as mean ± SD. RESULTS: Participants had an average RV of 6.33 ± 0.97 km/h (3.93 ± 0.6 mph), and reported an AV of 91.9 ± 24.5 km/wk (57.1 ± 15.2 miles/wk) and a PV of 141.0 ± 47.2 km/wk (87.6 ± 29.3 miles/wk). We observed significant associations between RV and age (r(58) = -0.57, p r(58) = 0.41, p r(58) = 0.34, p R2 = 0.37; F(3,56) = 12.4, pb1 = 0.013; t(56) = 2.57, p = 0.013), resulting in a 0.33 km/h increase in RV for every 25-km increase in AV. Last, significant relations existed between RV and AIx (r(58) = -0.30, p = 0.022); and RHR (r(58) = -0.26, p = 0.046). CONCLUSION: We found that (1) average weekly training volume is a significant predictor of performance in elite ultra-marathon athletes and (2) race performance was inversely associated with resting arterial wave reflection characteristics and heart rate

Validity and Reliability of the VO2 Master Pro for Oxygen Consumption and Ventilation Assessment

International Journal of Exercise Science 13(4): 1382-1401, 2020. This study assessed validity and reliability of the VO2 Master Pro portable metabolic analyzer for assessment of oxygen consumption (VO2) and minute ventilation (VE). In Protocol 1, eight male participants (height: 182.6 ± 5.8 cm, weight: 79.6 ± 8.3 kg, age: 41.0 ± 12.3 years) with previous competitive cycling experience completed an hour-long stationary cycling protocol twice, progressing from 100-300 Watts every 10 minutes while wearing the VO2 Master and a criterion measure (Parvomedics) for five minutes each, at each stage. In Protocol 2, 16 recreationally active male participants (height: 168.2 ± 8.4 cm, weight: 76.5 ± 13.3 kg, age: 23.0 ± 9.4 years) completed three incremental, maximal stationary cycling tests wearing one of three analyzers for each test (VO2 Master version 1.1.1, VO2 Master version 1.2.1, Parvomedics). For Protocol 1 and convergent validity, the VO2Master had mean absolute differences from the Parvomedics of \u3c0.3 L/min for absolute VO2 and \u3c5 L/min for VE overall and at each exercise stage. Mean absolute percent differences (MAPD) for VO2 and VE were \u3c9% overall and \u3c12% at each stage. Test-retest reliability of the VO2 Master (MAPD: 8.9-10.9%) was somewhat poorer than the Parvomedics (MAPD: 5.3-7.6%). For Protocol 2, validity was similar for both VO2 Master models (MAPD ~12% overall) compared to the Parvomedics for VO2 and VE. The VO2 Master had an acceptable validity and test-retest reliability for most intensities tested and may be an appealing option for field-based VO2 and VE analysis

Does Wim Hof Method Improve Breathing Economy during Exercise?

(1) Background: Breathing economy during endurance sports plays a major role in performance. Poor breathing economy is mainly characterized by excessive breathing frequency (BF) and low tidal volume (VT) due to shallow breathing. The purpose of this study was to evaluate whether a 4 week intervention based on the Wim Hof breathing method (WHBM) would improve breathing economy during exercise in adolescent runners. (2) Methods: 19 adolescent (16.6 ± 1.53 years) middle- and long-distance runners (11 boys and 8 girls) participated in the study. Participants were randomly divided into experimental (n = 11) and control groups (n = 8). The study was set in the transition period between competitive race seasons and both groups had a similar training program in terms of running volume and intensity over the course of the study. The experimental group performed breathing exercises every day (~20 min/day) for 4 weeks. The control group did not perform any kind of breathing exercise. The breathing exercises consisted of three sets of controlled hyperventilation and consecutive maximum breath holds. Before and after the intervention, participants performed incremental cycle ergometer testing sessions consisting of two minute stages at 1, 2, 3, and 4 W·kg−1 with breath-by-breath metabolic analysis. During the testing sessions, BF, VT, and minute ventilation (VE) were assessed and compared. (3) Results: There were no statistically significant differences (p > 0.05) in BF, VT, or VE between experimental and control groups before or after the intervention. A nonsignificant small-to-large effect for an increase in VE and BF in both groups following the 4 week intervention period was observed, possibly due to a reduction in training volume and intensity owing to the down period between competitive seasons. (4) Conclusions: The 4 week intervention of WHBM did not appear to alter parameters of breathing economy during a maximal graded exercise test in adolescent runners

THE EFFECT OF FEMALE AGING ON BLOOD PRESSURE AND SYMPATHETIC REACTIVITY DURING END-EXPIRATORY APNEA

BACKGROUND: Older females (OF) have greater cardiovascular risk and blood pressure (BP) reactivity compared to younger females (YF). In cohorts of males and females, aging augments BP reactivity and reduces sympathetic reactivity to chemoreflex stimulation. However, there is limited data on how aging affects BP reactivity to chemoreflex stimulation in females. Therefore, we tested the hypothesis that OF vs. YF would exhibit greater BP reactivity and a lower sympathetic reactivity during an end-expiratory breath-hold (EEBH; chemoreflex stimulus). METHODS: We measured beat-to-beat BP and Modelflow-derived hemodynamics (photoplethysmography; 13 YF, 8 OF) during a two-minute rest and maximal voluntary duration EEBH. In a subset, we also measured muscle sympathetic nerve activity (MSNA via microneurography; 9 YF, 5 OF). We tested YF during the early follicular phase and OF were post-menopausal. We compared variables at rest and in response to the EEBH between groups using unpaired, two-tailed t-tests for normally distributed data and Mann-Whitney U tests for non-normally distributed data. All data are presented as OF vs. YF with mean±SD or median[IQR]. RESULTS: Age (OF 66±6 vs. YF 23±2 years, p\u3c0.001), but not BMI (OF 21.8[3.7] vs. YF 22.6[3.6] kg/m2, p=0.491), was different between groups. OF had a longer EEBH duration (OF 46[28] vs. YF 29[9] s, p\u3c0.001). At rest, mean BP (OF 99±13 vs. YF 81±4 mmHg, p\u3c0.001), MSNA burst frequency (OF 32±9 vs. YF 9±7 bursts/min, p\u3c0.001), and MSNA total activity (OF 802±296 vs. YF 90±121 AU, p\u3c0.001) were higher in OF. The change in MAP (OF 27[10] vs. YF 15[13] mmHg, p=0.045) was larger in OF whereas the relative change in MSNA total activity (OF 369±182 vs. YF 1014±620 %, p=0.014) was smaller in OF during the EEBH. However, the increases in MSNA burst frequency (OF 15±7 vs. YF 16±9 bursts/min, p=0.833) during the EEBH were not different between groups. Additionally, the change in cardiac output was lower in OF (OF -0.3±0.5 vs. YF 0.2±0.3 L/min, p=0.005) but the change in systemic vascular resistance was greater in OF (OF 9.4±2.8 vs. YF 3.2±1.9 mmHg/L/min, p\u3c0.001). CONCLUSION: The smaller relative increases in MSNA total activity during EEBH in OF suggest reduced chemoreflex sensitivity in female aging. Interestingly, these preliminary data suggest that augmented BP reactivity in OF was driven by vascular resistance despite smaller increases in MSNA during EEBH

Validation of the SmartPlate for detecting food weight and type

This study determined accuracy (comparing to criterion), inter-plate reliability (comparing measures between two plates), and intra-plate reliability (comparing successive measures on one plate) of the SmartPlate for food weight and type. Food weight validation included comparing SmartPlate weights to criterion [reference] scale weights (1,980 measures) and weights of 188 foods (2,256 measures). Food type validation included assessing SmartPlate accuracy for 188 foods. For weight, mean absolute percent errors for accuracy, inter-plate reliability, and intra-plate reliability were 6.2, 7.4, and 4.9%, respectively. For food type, foods were correctly identified/listed or searchable 67.0 or 98.9% of the time, respectively, with 76.0% inter-plate reliability and 86.3% intra-plate reliability. The SmartPlate had acceptable accuracy and reliability for assessing food weight and type and may be appealing for monitoring dietary surveillance or intervention. Due to high intra-plate reliability, the SmartPlate may be especially useful for one-on-one interventions and assessing change over time.</p

THE EFFECT OF FEMALE AGING ON SYMPATHETIC TRANSDUCTION DURING THE COLD PRESSOR TEST

BACKGROUND: Older female adults (OF) have the highest risk for hypertension and cardiovascular disease among any demographic in America. Exaggerated blood pressure (BP) responses during the cold pressor test (CPT) are associated with higher cardiovascular disease risk. However, previous studies report no age-related differences in BP or sympathetic responses during the CPT in females, but data are limited and partly confounded by differences in body mass index (BMI), which can independently influence CPT responses. Therefore, we tested the hypothesis that aging increases BP and sympathetic responses during the CPT in OF (\u3e55 years) compared with YF (18 - 35 years) matched for BMI. METHODS: We studied nine post-menopausal OF and 17 YF (early follicular phase) with brachial BP \u3c140/90 mmHg and BMI \u3c30 kg/m2. We measured mean BP (photoplethysmography) during a 10-min rest period and a 2-min CPT. In a subset (6 OF, 10 YF), we also measured muscle sympathetic nerve activity (MSNA; microneurography). We calculated time-averaged sympathetic transduction of BP during the CPT (CPT-baseline) as sympathetic-pressure ratios (mean BP/MSNA burst frequency & mean BP/MSNA total activity). We compared age groups using unpaired, two-tailed t-tests for normally distributed data and Mann-Whitney U tests for non-normally distributed data (i.e., failed Shapiro-Wilk test). RESULTS: The data are presented as OF vs. YF with mean±SD or median[IQR]. By design, age (66±6 vs. 24±4 years, p\u3c0.0001), but not BMI (22.8±2.8 vs. 22.6±3.5 kg/m2, p=0.85), was higher in OF. Mean BP (97±13 vs. 78±4 mmHg, p\u3c0.0001), MSNA burst frequency (35±6 vs. 11±6 bursts/min, p\u3c0.0001), and MSNA total activity (1096[559] vs. 114[147] AU, p=0.001) were higher in OF at rest. Mean BP responses during the CPT did not differ between groups (∆17±9 vs. 14±8 mmHg, p=0.79). However, MSNA burst frequency (∆7±5 vs. 17±11 bursts/min, p=0.01) and total activity (∆24[93] vs. 514[3648] %, p\u3c0.001) responses during the CPT were higher in YF. Finally, the sympathetic-pressure ratios did not differ between groups (1.6[13.7] vs. 0.7[0.4] mmHg/bursts/min, p=0.09 & 0.25[1.69] vs. 0.02[0.04] mmHg/%, p=0.40). CONCLUSION: In partial support of our hypothesis, these preliminary data suggest that MSNA, but not BP, responses during the CPT are attenuated in OF. A higher baseline MSNA in OF relative to YF may explain these reduced sympathetic responses during the CPT

ASSOCIATION BETWEEN RESTING HEART RATE VARIABILITY AND NOCTURNAL BLOOD PRESSURE IN YOUNG ADULTS

BACKGROUND: Healthy circadian variation in arterial blood pressure (BP) is characterized by nocturnal dipping. Elevated BP or attenuated BP dipping during sleep is associated with greater risk for cardiovascular diseases. Moreover, cardiac-autonomic activity is associated with BP dipping patterns in clinical populations, but whether this relationship exists in apparently healthy adults is unclear. Therefore, the purpose of this study was to quantify associations between cardiac-autonomic activity, indexed via resting heart rate variability (HRV), and nocturnal BP characteristics in young adults. METHODS: Twenty-nine apparently healthy young adults (n = 13 males, 23 ± 4 yrs, 23 ± 3 kg/m2, n = 16 females, 20 ± 2 yrs, 23 ± 3 kg/m2) were included in the analysis. Resting HRV was obtained in the laboratory following an overnight fast. Five-minute electrocardiographic recordings were obtained in the supine position following a five-minute stabilization period. Short-term HRV parameters of interest included the mean RR interval, standard deviation of normal RR intervals (SDNN), and root-mean square of successive differences (RMSSD). Participants left the laboratory wearing an ambulatory BP monitor on their upper arm programmed to perform recordings every 20 minutes during awake hours and every 30 minutes during sleeping hours. Self-reported bedtime and wake time were used to identify awake and asleep periods. Absolute BP dipping was quantified as awake BP minus asleep BP. RESULTS: In males, asleep diastolic BP (54.7 ± 4.1 mmHg) was associated with SDNN (58.7 ± 17.9 ms, r = -0.57, P \u3c0.05) and RMSSD (60.5 ± 25.9 ms, r = -0.56, P \u3c0.05). Additionally, systolic BP (12.1 ± 6.6 mmHg, r = 0.64) and diastolic BP dipping (22.8 ± 7.4 mmHg, r = 0.59) were associated with SDNN (Ps \u3c0.05). No associations between any HRV and BP values were observed for females (Ps \u3e0.05). CONCLUSIONS: Our findings reveal sex differences in the association between resting short-term cardiac-autonomic activity and nocturnal BP characteristics in healthy young adults. HRV is an accessible and modifiable (e.g., via aerobic exercise) biomarker that may be a useful target for young adult males to improve circadian variation in BP and reduce cardiovascular disease risk. FUNDING: Supported by Georgia Southern University Faculty Research Committee Research Seed Funding Award

Comparison of the activPAL CREA and VANE algorithms for characterization of posture and activity in free-living adults

Background: The activPAL accelerometer is used widely for assessment of free-living activity and postural data. Two algorithms, VANE (traditional) and CREA (new), are available to analyze activPAL data, but the comparability of metrics derived from these algorithms is unknown. Purpose: To determine the comparability of physical activity and sedentary behavior metrics from activPAL’s VANE and CREA algorithms. Methods: Individuals enrolled in the LIFT trial (n = 354) wore an activPAL accelerometer on the right thigh continuously for 7 days on four occasions, resulting in 5,851 valid days of data for analysis. Daily data were downloaded in the PALbatch software using the VANE and CREA algorithms. Correlations, mean absolute percentage error, effect sizes (ES), and equivalence (within 3%) were calculated to evaluate comparability of the algorithms. Results: Steps, activity score, stepping time, bouts of stepping, and upright time metrics were statistically equivalent, highly correlated (r ≥ .98), and had small mean absolute percentage errors (≤2.5%) and trivial ES (ES &lt; 0.07) between algorithms. Stepping bouts also had good comparability. Conversely, sedentary-upright and upright-sedentary transitions and bouts of sitting were not equivalent, with large mean absolute percentage differences (17.4%–141.3%) and small to very large ES (ES = 0.45–3.80) between algorithms. Conclusions: Stepping and upright metrics are highly comparable between activPAL’s VANE and CREA algorithms, but sitting metrics had large differences as the VANE algorithm does not capture nonwear or differentiate between sitting and lying down. Researchers using the activPAL should explicitly describe the analytic algorithms used in their work to facilitate data pooling and comparability across studies