Michael R. Esco

Validity of the ithlete TM Smart Phone Application for Determining Ultra-Short-Term Heart Rate Variability

Abstract The purpose of this investigation was to cross-validate the ithleteTM heart rate variability smart phone application with an electrocardiograph for determining ultra-short-term root mean square of successive R-R intervals. The root mean square of successive R-R intervals was simultaneously determined via electrocardiograph and ithleteTM at rest in twenty five healthy participants. There were no significant differences between the electrocardiograph and ithleteTM derived root mean square of successive R-R interval values (p > 0.05) and the correlation was near perfect (r = 0.99, p < 0.001). In addition, the ithleteTM revealed a Standard Error of the Estimate of 1.47 and Bland Altman plot showed that the limits of agreement ranged from 2.57 below to 2.63 above the constant error of -0.03. In conclusion, the ithleteTM appeared to provide a suitably accurate measure of root mean square of successive R-R intervals when compared to the electrocardiograph measures obtained in the laboratory within the current sample of healthy adult participants. The current study lays groundwork for future research determining the efficacy of ithleteTM for reflecting athletic training status over a chronic conditioning period.

Electromyographical Comparison of Plank Variations Performed With and Without Instability Devices

Abstract Snarr, RL and Esco, MR. Electromyographical comparison of plank variations performed with and without instability devices. J Strength Cond Res 28(11): 3298–3305, 2014—Although there are multiple studies involving abdominal musculature activation and instability devices (e.g., Swiss balls), there is minimal research comparing them with a suspension device (e.g., TRX). The purpose of this investigation was to measure the electromyographical (EMG) activity of the rectus abdominis (RA), external oblique (EO), and erector spinae while performing planks with and without multiple instability devices. Twelve apparently healthy men (n = 6; age = 23.92 ± 3.64 years) and women (n = 6; age = 22.57 ± 1.87 years) volunteered to participate in this study. All participants performed 2 isometric contractions of 5 different plank variations, with or without an instability device, where the order of the exercises was randomized. Mean peak and normalized EMG of the RA, EO, and erector spinae musculature were compared across the 5 exercises. Results indicated that planks performed with the instability devices increased EMG activity in the superficial musculature when compared with traditional stable planks. Therefore, a traditional plank performed on a labile device may be considered an advanced variation and appropriate for use when a greater challenge is warranted. However, caution should be taken for those individuals with a history or weakness in the lumbar region due to the increases in erector spinae activation during instability planks.

Comparison of total and segmental body composition using DXA and multifrequency bioimpedance in collegiate female athletes.

Abstract Esco, MR, Snarr, RL, Leatherwood, MD, Chamberlain, NA, Redding, ML, Flatt, AA, Moon, JR, and Williford, HN. Comparison of total and segmental body composition using DXA and multifrequency bioimpedance in collegiate female athletes. J Strength Cond Res 29(4): 918–925, 2015—The purpose of this investigation was to determine the agreement between multifrequency bioelectrical impedance analysis (BIA) and dual-energy x-ray absorptiometry (DXA) for measuring body fat percentage (BF%), fat-free mass (FFM), and total body and segmental lean soft tissue (LST) in collegiate female athletes. Forty-five female athletes (age = 21.2 ± 2.0 years, height = 166.1 ± 7.1 cm, weight = 62.6 ± 9.9 kg) participated in this study. Variables measured through BIA and DXA were as follows: BF%, FFM, and LST of the arms (ARMSLST), the legs (LEGSLST), the trunk (TRUNKLST), and the total body (TOTALLST). Compared with the DXA, the InBody 720 provided significantly lower values for BF% (−3.3%, p < 0.001) and significantly higher values for FFM (2.1 kg, p < 0.001) with limits of agreement (1.96 SD of the mean difference) of ±5.6% for BF% and ±3.7 kg for FFM. No significant differences (p < 0.008) existed between the 2 devices (InBody 720—DXA) for ARMSLST (0.05 kg), TRUNKLST (0.14 kg), LEGSLST (−0.4 kg), and TOTALLST (−0.21 kg). The limits of agreement were ±0.79 kg for ARMSLST, ±2.62 kg for LEGSLST, ±3.18 kg for TRUNKLST, and ±4.23 kg for TOTALLST. This study found discrepancies in BF% and FFM between the 2 devices. However, the InBody 720 and DXA appeared to provide excellent agreement for measuring total body and segmental LST. Therefore, the InBody 720 may be a rapid noninvasive method to assess LST in female athletes when DXA is not available.

Heart rate variability stabilization in athletes: towards more convenient data acquisition

Resting heart rate variability (HRV) is a potentially useful marker to consider for monitoring training status in athletes. However, traditional HRV data collection methodology requires a 5‐min recording period preceded by a 5‐min stabilization period. This lengthy process may limit HRV monitoring in the field due to time constraints and high compliance demands of athletes. Investigation into more practical methodology for HRV data acquisitions is required. The aim of this study was to determine the time course for stabilization of ECG‐derived lnRMSSD from traditional HRV recordings. Ten‐minute supine ECG measures were obtained in ten male and ten female collegiate cross‐country athletes. The first 5 min for each ECG was separately analysed in successive 1‐min intervals as follows: minutes 0–1 (lnRMSSD0–1), 1–2 (lnRMSSD1–2), 2–3 (lnRMSSD2–3), 3–4 (lnRMSSD3–4) and 4–5 (lnRMSSD4–5). Each 1‐min lnRMSSD segment was then sequentially compared to lnRMSSD of the 5‐ to 10‐min ECG segment, which was considered the criterion (lnRMSSDCriterion). There were no significant differences between each 1‐min lnRMSSD segment and lnRMSSDCriterion, and the effect sizes were considered trivial (ES ranged from 0·07 to 0·12). In addition, the ICC for each 1‐min segment compared to the criterion was near perfect (ICC values ranged from 0·92 to 0·97). The limits of agreement between the prerecording values and lnRMSSDCriterion ranged from ±0·28 to ±0·45 ms. These results lend support to shorter, more convenient ECG recording procedures for lnRMSSD assessment in athletes by reducing the prerecording stabilization period to 1 min.

The accuracy of the body adiposity index for predicting body fat percentage in collegiate female athletes.

Abstract Esco, MR. The accuracy of the body adiposity index for predicting body fat percentage in collegiate female athletes. J Strength Cond Res 27(6): 1679–1683, 2013—The body adiposity index (BAI) is a new simplistic method for predicting body fat percentage (BF%) via a simple equation of hip circumference to height. A scientific study of this novel method in athletic groups is warranted because of the possibility of it serving as an inexpensive field technique. The purpose of this study was to cross-validate the BAI for predicting BF% in a group of collegiate female athletes by using dual-energy x-ray absorptiometry (DXA) as the criterion variable. Thirty college-aged female athletes (age = 20.0 ± 1.3 years) participated in this study. For each participant, BF% was obtained with the BAI method and compared with DXA. The mean BF% was 27.1 ± 3.4 by the BAI and 26.7 ± 5.9 from DXA, which was not significantly different (p > 0.05). However, the BAI did not provide a significant correlation with the DXA (r = 0.28, R2 = 0.08, p > 0.05) and resulted in a standard error of estimate = 5.78% and total error = 5.84%. Bland-Altman plot showed that the limits of agreement (95% confidence intervals) between the DXA and BAI ranged between −10.2 and 11.8%, and there was a significant negative association between the difference and mean of the 2 methods (r = −0.52, p < 0.01). The results of this investigation indicate that BAI results in large individual errors when predicting BF% in female athletes and has a tendency to provide overestimated values as BF% decreases. Therefore, this method should not be used for predicting individual BF% in athletic women.

SKINFOLD THICKNESS IS RELATED TO CARDIOVASCULAR AUTONOMIC CONTROL AS ASSESSED BY HEART RATE VARIABILITY AND HEART RATE RECOVERY

Esco, MR, Williford, HN, and Olson, MS. Skinfold thickness is related to cardiovascular autonomic control as assessed by heart rate variability and heart rate recovery. J Strength Cond Res 25(8): 2304-2310, 2011—The purpose of this study was to determine if heart rate recovery (HRR) and heart rate variability (HRV) are related to maximal aerobic fitness and selected body composition measurements. Fifty men (age = 21.9 ± 3.0 years, height = 180.8 ± 7.2 cm, weight = 80.4 ± 9.1 kg, volunteered to participate in this study. For each subject, body mass index (BMI), waist circumference (WC), and the sum of skinfolds across the chest, abdomen, and thigh regions (SUMSF) were recorded. Heart rate variability (HRV) was assessed during a 5-minute period while the subjects rested in a supine position. The following frequency domain parameters of HRV were recorded: normalized high-frequency power (HFnu), and low-frequency to high-frequency power ratio (LF:HF). To determine maximal aerobic fitness (i.e., &OV0312;O2max), each subject performed a maximal graded exercise test on a treadmill. Heart rate recovery was recorded 1 (HRR1) and 2 (HRR2) minutes during a cool-down period. Mean &OV0312;O2max and BMI for all the subjects were 49.5 ± 7.5 ml·kg−1·min−1 and 24.7 ± 2.2 kg·m−2, respectively. Although &OV0312;O2max, WC, and SUMSF was each significantly correlated to HRR and HRV, only SUMSF had a significant independent correlation to HRR1, HRR2, HFnu, LF:HF (p < 0.01). The results of the regression procedure showed that SUMSF accounted for the greatest variance in HRR1, HRR2, HFnu, and LF:HF (p < 0.01). The results of this study suggest that cardiovascular autonomic modulation is significantly related to maximal aerobic fitness and body composition. However, SUMSF appears to have the strongest independent relationship with HRR and HRV, compared to other body composition parameters and &OV0312;O2max.

Evaluating Individual Training Adaptation With Smartphone-Derived Heart Rate Variability in a Collegiate Female Soccer Team.

Abstract Flatt, AA and Esco, MR. Evaluating individual training adaptation with Smartphone-derived heart rate variability in a collegiate female soccer team. J Strength Cond Res 30(2): 378–385, 2016—Monitoring individual responses throughout training may provide insight to coaches regarding how athletes are coping to the current program. It is unclear if the evolution of heart rate variability (HRV) throughout training in team-sport athletes can be useful in providing early indications of individual adaptation. This study evaluated relationships between changes in resting cardiac autonomic markers derived from a novel smartphone device within the first 3 weeks of a 5-week conditioning program and the eventual change in intermittent running performance at week 5 among 12 collegiate female soccer players. Change variables from weeks 1 to 3 of the weekly mean and weekly coefficient of variation for resting heart rate ([INCREMENT]RHRmean and [INCREMENT]RHRcv, respectively) and log-transformed root mean square of successive R-R intervals multiplied by 20 ([INCREMENT]Ln rMSSDmean and [INCREMENT]Ln rMSSDcv, respectively) were compared with changes in Yo-Yo Intermittent Recovery Test Level 1 performance ([INCREMENT]Yo-Yo). A very large and significant correlation was found between [INCREMENT]Yo-Yo and [INCREMENT]Ln rMSSDcv (r = −0.74; p = <0.01) and a large nonsignificant correlation was found with [INCREMENT]Ln rMSSDmean (r = 0.50; p = 0.096). This study suggests that a decrease in Ln rMSSDcv within the first 3 weeks of training is a favorable response, indicative of positive adaptation. Collecting daily HRV data with a smartphone application using ultrashort HRV measures seems useful for athlete monitoring.

Relationship of push-ups and sit-ups tests to selected anthropometric variables and performance results: a multiple regression study.

Esco, MR, Olson, MS, and Williford, H. Relationship of push-ups and sit-ups tests to selected anthropometric variables and performance results: a multiple regression study. J Strength Cond Res 22(6): 1862-1868, 2008-The purpose of this study was to explore whether selected anthropometric measures such as specific skinfold sites, along with weight, height, body mass index (BMI), waist and hip circumferences, and waist/hip ratio (WHR) were associated with sit-ups (SU) and push-ups (PU) performance, and to build a regression model for SU and PU tests. One hundred apparently healthy adults (40 men and 60 women) served as the subjects for test validation. The subjects performed 60-second SU and PU tests. The variables analyzed via multiple regression included weight, height, BMI, hip and waist circumferences, WHR, skinfolds at the abdomen (SFAB), thigh (SFTH), and subscapularis (SFSS), and sex. An additional cohort of 40 subjects (17 men and 23 women) was used to cross-validate the regression models. Validity was confirmed by correlation and paired t-tests. The regression analysis yielded a four-variable (PU, height, SFAB, and SFTH) multiple regression equation for estimating SU (R2 = 0.64, SEE = 7.5 repetitions). For PU, only SU was loaded into the regression equation (R2 = 0.43, SEE = 9.4 repetitions). Thus, the variables in the regression models accounted for 64% and 43% of the variation in SU and PU, respectively. The cross-validation sample elicited a high correlation for SU (r = 0.87) and PU (r = 0.79) scores. Moreover, paired-samples t-tests revealed that there were no significant differences between actual and predicted SU and PU scores. Therefore, this study shows that there are a number of selected, health-related anthropometric variables that account significantly for, and are predictive of, SU and PU tests.

Electromyographic Comparison of Traditional and Suspension Push-Ups

Abstract There is very limited scientific data concerning suspension training. The purpose of this investigation was to compare the electromyographic activity of the pectoralis major, anterior deltoid, and triceps brachii between a suspension push-up and traditional push-up. Twenty-one apparently healthy men (n = 15, age = 25.93 ± 3.67 years) and women (n = 6, age = 23.5 ± 1.97 years) volunteered to participate in this study. All subjects performed four repetitions of a suspension push-up and a traditional push-up where the order of the exercises was randomized. The mean peak and normalized electromyography of the pectoralis major, anterior deltoid, and triceps brachii were compared across the two exercises. Suspension push-ups elicited the following electromyographic values: pectoralis major (3.08 ± 1.13 mV, 69.54 ± 27.6 %MVC), anterior deltoid (5.08 ± 1.55 mV, 81.13 ± 17.77 %MVC), and triceps brachii (5.11 ± 1.97 mV, 105.83 ± 18.54 %MVC). The electromyographic activities during the traditional push-up were as follows: pectoralis major (2.66 ± 1.05 mV, 63.62 ± 16.4 %MVC), anterior deltoid (4.01 ± 1.27 mV, 58.91 ± 20.3 %MVC), and triceps brachii (3.91 ± 1.36 mV, 74.32 ± 16.9 %MVC). The mean peak and normalized electromyographic values were significantly higher for all 3 muscles during the suspension push-up compared to the traditional push-up (p < 0.05). This study suggests that the suspension push-up elicited a greater activation of pectoralis major, anterior deltoid, and triceps brachii when compared to a traditional push-up. Therefore, suspension push-ups may be considered an advanced variation of a traditional push-up when a greater challenge is warranted.

The Accuracy of Hand-to-Hand Bioelectrical Impedance Analysis in Predicting Body Composition in College-Age Female Athletes

Esco, MR, Olson, MS, Williford, HN, Lizana, SN, and Russell, AR. The accuracy of hand-to-hand bioelectrical impedance analysis in predicting body composition in college-age female athletes. J Strength Cond Res 25(4): 1040-1045, 2011-The purpose of this investigation was to determine the accuracy of hand-to-hand bioelectrical impedance analysis (BIA) for estimating body composition in college-age female athletes using dual-energy X-ray absorptiometry (DEXA) as the criterion measure. Forty National Association for Intercollegiate Athletics college female athletes volunteered to participate in this study. For each participant, total body fat percentage (BF%) and fat-free mass (FFM) were obtained via BIA and DEXA. The mean BF% and FFM values obtained by BIA were compared with the criterion DEXA measure. The DEXA strongly correlated to the BIA for BF% (r = 0.74, R2 = 0.55, SEE = 3.60, and p < 0.01) and FFM (r = 0.84, R2 = 0.71, SEE = 2.45, p < 0.01). However, when compared with the DEXA, the mean values for BIA were significantly lower for BF% (DEXA = 27.6 ± 5.3%, BIA = 22.5 ± 3.5%, p < 0.01) and higher for FFM (DEXA = 47.2 ± 4.5 kg, BIA = 50.6 ± 4.6 kg, p < 0.01). The results of this investigation indicate that hand-to-hand BIA significantly underestimates BF% and overestimated FFM in college-age female athletes when compared with the criterion DEXA. Practitioners should use caution when analyzing body composition with hand-held BIA in a population of athletic women.