DSpace Repository :: Browsing by Author "Hornikel, Bjoern"

Browsing by Author "Hornikel, Bjoern"

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Accuracy of a Mobile 2D Imaging System for Body Volume and Subsequent Composition Estimates in a Three-Compartment Model
(Lippincott Williams & Wilkins, 2021) Fedewa, Michael V.; Sullivan, Katherine; Hornikel, Bjoern; Holmes, Clifton J.; Metoyer, Casey J.; Esco, Michael R.; University of Alabama Tuscaloosa
Purpose The purpose of the study was to compare a single two-dimensional image processing system (IMAGE) to underwater weighing (UWW) for measuring body volume (BV) and subsequently estimating body fat percentage (%Fat), fat mass (FM), and fat-free mass (FFM) via a 3-compartment (3C) model. Methods A sample of participants age 18-39 yr was recruited for this study (n = 67, 47.8% female). BV was measured with UWW and predicted via the IMAGE software. The BV estimates from UWW (3C(UWW)) and IMAGE (3C(IMAGE)) were separately combined with constant total body water and body mass values for 3C model calculation of %Fat, FM, and FFM. Results BV obtained from the IMAGE was 67.76 +/- 12.19 and 67.72 +/- 12.04 L from UWW, which was not significantly different (P = 0.578) and very largely correlated (r = 0.99, P < 0.001). When converted to %Fat (3C(UWW) = 21.01% +/- 7.30%, 3C(IMAGE) = 21.08% +/- 7.04%, P = 0.775), FM (3C(UWW) = 14.68 +/- 5.15 kg, 3C(IMAGE) = 14.78 +/- 5.08 kg, P = 0.578), and FFM (3C(UWW) = 57.00 +/- 13.20 kg, 3C(IMAGE) = 56.90 +/- 12.84 kg, P = 0.578) with the 3C model, no significant mean differences and very large correlations (r values ranged from 0.96 to 0.99) were observed. In addition, the standard error of estimate, total error, and 95% limits of agreement for all three metrics were small and considered acceptable. Conclusions An IMAGE system provides valid estimates of BV that accurately estimates body composition in a 3C model.
Agreement Between A 2-Dimensional Digital Image-Based 3-Compartment Body Composition Model and Dual Energy X-Ray Absorptiometry for The Estimation of Relative Adiposity
(Elsevier, 2022) Sullivan, Katherine; Metoyer, Casey J.; Hornikel, Bjoern; Holmes, Clifton J.; Nickerson, Brett S.; Esco, Michael R.; Fedewa, Michael, V; University of Alabama Tuscaloosa; Washington University (WUSTL); Texas A&M International University
The purpose of this study was to compare relative adiposity (%Fat) derived from a 2-dimensional image-based 3-component (3C) model (%Fat(3C-IMAGE)) and dual-energy X-ray absorptiometry (DXA) (%Fat(DXA)) against a 5-component (5C) laboratory criterion (%Fat(5C)). 57 participants were included (63.2% male, 84.2% White/Caucasian, 22.5 +/- 4.7 yrs., 23.9 +/- 2.8 kg/m(2)). For each participant, body mass and standing height were measured to the nearest 0.1 kg and 0.1 cm, respectively. A digital image of each participant was taken using a 9.7 inch, 16g iPad Air 2 and analyzed using a commercially available application (version 1.1.2, made Health and Fitness, USA) for the estimation of body volume (BV) and inclusion in %Fat(3C-IMAGE). %Fat(3C-IMAGE) and %Fat(5C) included measures of total body water derived from bioimpedance spectroscopy. The criterion %Fat(5C) included BV estimates derived from underwater weighing and bone mineral content measures via DXA. %Fat(DXA) estimates were calculated from a whole-body DXA scan. A standardized mean effect size (ES) assessed the magnitude of differences between models with values of 0.2, 0.5, and 0.8 for small, moderate, and large differences, respectively. Data are presented as mean +/- standard deviation. A strong correlation (r = 0.94, p <.001) and small mean difference (ES = 0.24, p <.001) was observed between %Fat(3C-IMAGE) (19.20 +/- 5.80) and %Fat(5C) (17.69 +/- 6.20) whereas a strong correlation (r = 0.87, p <.001) and moderate-large mean difference (ES = 0.70, p <.001) was observed between %Fat DXA (22.01 +/- 6.81) and %Fat(5C). Furthermore, %Fat(3C-IMAGE )(SEE = 2.20 %Fat, TE= 2.6) exhibited smaller SEE and TE than %Fat(DXA) (SEE = 3.14 %Fat, TE = 5.5). The 3C image-based model performed slightly better in our sample of young adults than the DXA 3C model. Thus, the 2D image analysis program provides an accurate and non-invasive estimate of %Fat within a 3C model in young adults. Compared to DXA, the 3C image-based model allows for a more cost-effective and portable method of body composition assessment, potentially increasing accessibility to multi-component methods.
Associations between Multimodal Fitness Assessments and Rowing Ergometer Performance in Collegiate Female Athletes
(MDPI, 2020) Holmes, Clifton J.; Hornikel, Bjoern; Sullivan, Katherine; Fedewa, Michael V.; Washington University (WUSTL); University of Alabama Tuscaloosa
The purpose was to examine the association of critical power from a three-minute all-out row (CP3-min) and peak power from a one-stroke maximum test (1-Stroke) with laboratory-based fitness assessments (peak oxygen consumption [(V)over dotO(2peak)] and Wingate anaerobic test [WAnT]) and 6000 m (6K) and 2000 m (2K) rowing ergometer performance. Thirty-one female collegiate rowers (20.2 +/- 1.1 years, 70.9 +/- 6.9 kg, and 172.2 +/- 4.8 cm) participated in fitness and rowing performance testing. Pearson's correlations, linear regression, and Cohen's q were used to determine statistical relationships. Absolute (V)over dotO(2peak) values displayed significant correlations with 6K(total) (-0.68), 6K(split) (-0.68), 2K(total) (-0.64), and 2K(split) (-0.43). Relative (V)over dotO(2peak) displayed significant correlations with 6K(total) (-0.36), and 6K(split) (-0.37). CP3-min demonstrated significant correlations with 6K(total) (-0.62), 6K(split) (-0.62), 2K(total) (-0.61), and 2K(split) (-0.99). For 2K(split), a significant difference was observed between relative (V)over dotO(2peak) and CP3-min correlations with a "large" effect size (q = 2.367). Furthermore, 1-Stroke showed significant associations with 6K(total) (-0.63), 6K(split) (-0.63), 2K(total) (-0.62), and 2K(split) (-0.44), while WAnT produced non-significant correlations. Absolute (V)over dotO(2peak) CP3-min accounted for significant proportions of variance observed with performance measures (p < 0.05). Practitioners should consider incorporating CP3-min and 1-Stroke as additional tests for gauging rowing performance.
The Efficacy of Blood Flow Restriction During High Intensity Resistance Exercise
(University of Alabama Libraries, 2021) Hornikel, Bjoern; Winchester, Lee J; University of Alabama Tuscaloosa
Blood flow restriction (BFR) resistance training has demonstrated its effectiveness for inducing hypertrophic adaptations at much lower intensities (20-30% one-repetition maximum (1RM)) compared to traditional high-intensity (>65% 1RM) recommendations. Limited research has examined BFR in conjunction with high-intensity resistance training, with mixed results. The purpose of this dissertation was to expand upon this understudied area with a series of three studies to 1) better understand blood flow responses in the lower limbs with varying occlusion pressures, 2) determine the effect of high-intensity BFR (HI-BFR) resistance exercise on fatigue, ratings of perceived exertion (RPE), and pain, and 3) examine the influence of HI-BFR on metabolic stress, muscle damage, and hypoxia. Study 1 examined the effects of varying BFR occlusion pressures on blood flow volume in the legs. Results indicate a potential 50% limb occlusion pressure (LOP) threshold at which point statistically significant reductions in blood flow volume occur in the posterior tibial artery. An observed plateau in blood flow reductions between 60-80%LOP indicates the potential for reduced occlusion pressure during exercise. Study 2 examined the effects of HI-BFR on inter-set fatigue, RPE, and Pain, in addition to post-exercise neuromuscular fatigue/impairment. Significantly greater number of total repetitions and repetitions during sets 1, 2, and 4 (p < .05) were performed in the CTRL condition. Although RPE between conditions was similar across all sets (p ≥ .05), perceived pain was significantly greater in BFR across all sets (p < .05). Changes in neuromuscular performance measures were consistent across exercise conditions. Study 3 investigated the effect of HI-BFR on metabolic stress, muscle swelling, and muscle damage in response to a back-squat protocol. Significantly lower blood lactate concentrations were measured following the BFR exercise stimulus, compared to CTRL (p = .001). No significant differences in muscle swelling were observed between conditions. Post-exercise interleukin-6 was significantly greater following the BFR exercise (p = .007). The use of BFR during high-intensity resistance exercise seems to be a useful method for advanced induction of fatigue during exercise, although the reduced exercise volume due to fatigue and pain limits the overall acute hypertrophic mechanistic responses.
Generalized Equations for Predicting Percent Body Fat from Anthropometric Measures Using a Criterion Five-Compartment Model
(Lippincott Williams & Wilkins, 2021) Cicone, Zackary S.; Nickerson, Brett S.; Choi, Youn-Jeng; Holmes, Clifton J.; Hornikel, Bjoern; Fedewa, Michael, V; Esco, Michael R.; Shenandoah University; University of Alabama Tuscaloosa; Texas A&M International University; Ewha Womans University; Washington University (WUSTL)
Introduction: Anthropometric-based equations are used to estimate percent body fat (%BF) when laboratory methods are impractical or not available. However, because these equations are often derived from two-compartment models, they are prone to error because of the assumptions regarding fat-freemass composition. The purpose of this study was to develop a new anthropometric-based equation for the prediction of%BF, using a five-compartment (5C) model as the criterion measure. Methods: A sample of healthy adults (52.2% female; age, 18 to 69 yr; body mass index, 15.7 to 49.5 kg.m(-2)) completed hydrostatic weighing, dual-energy x-ray absorptiometry, and bioimpedance spectroscopy measurements for calculation of 5C%BF (%BF5C), as well as skinfolds and circumferences.%BF5C was regressed on anthropometric measures using hierarchical variable selection in a random sample of subjects (n = 279). The resulting equation was cross-validated in the remaining participants (n = 78). New model performance was also comparedwith several common anthropometric-based equations. Results: The new equation [%BFNew = 6.083 + (0.143 x SSnew) - (12.058 x sex) - (0.150 x age) - (0.233 x body mass index) + (0.256 x waist) + (0.162 x sex x age)] explained a significant proportion of variance in %BF5C (R-2 = 0.775, SEE = 4.0%). Predictors included sum of skinfolds (SSnew, midaxillary, triceps, and thigh) and waist circumference. The new equation cross-validated well against %BF5C when compared with other existing equations, producing a large intraclass correlation coefficient (0.90), small mean bias and limits of agreement (0.4% +/- 8.6%), and small measures of error (SEE = 2.5%). Conclusions: %BFNew improved on previous anthropometric-based equations, providing better overall agreement and less error in %BF estimation. The equation described in this study may provide an accurate estimate of %BF5C in healthy adults when measurement is not practical.
Heart-Rate Variability Recording Time and Performance in Collegiate Female Rowers
(Human Kinetics, 2021) Sherman, Sara R.; Holmes, Clifton J.; Hornikel, Bjoern; MacDonald, Hayley, V; Fedewa, Michael, V; Esco, Michael R.; University of Alabama Tuscaloosa; University of Illinois Chicago; University of Illinois Chicago Hospital
Purpose: To assess the agreement of the root mean square of successive R-R interval (RMSSD) values when recorded immediately upon waking to values recorded later in the morning prior to practice, and to determine the associations of the RMSSD recordings with performance outcomes in female rowers. Methods: A total of 31 National Collegiate Athletic Association Division I rowers were monitored for 6 consecutive days. Two seated RMSSD measurements were obtained on at least 3 mornings using a smartphone-based photoplethysmography application. Each 1-minute RMSSD measure was recorded following a 1-minute stabilization period. The first (T1) measurement occurred at the athlete's home following waking, while the second (T2) transpired upon arrival at the team's boathouse immediately before practice. From the measures, the RMSSD mean and coefficient of variation were calculated. Two objective performance assessments were conducted on an indoor rowing ergometer on separate days: 2000-m time trial and distance covered in 30 minutes. Interteam rank was determined by the coaches, based on subjective and objective performance markers. Results: The RMSSD mean (intraclass correlation coefficient = .82; 95% CI,.63 to .92) and RMSSD coefficient of variation (intraclass correlation coefficient = .75; 95% CI,.48 to .88) were strongly correlated at T1 and T2, P < .001. The RMSSD mean at T1 and T2 was moderately associated with athlete rank (r = -.55 and r = -.46, respectively), 30-minute distance (r = .40 and r = .41, respectively), and 2000 m at T1 (r = -.37), P < .05. No significant correlations were observed for the RMSSD coefficient of variation. Conclusion: Ultrashort RMSSD measurements taken immediately upon waking show very strong agreement with those taken later in the morning, at the practice facility. Future research should more thoroughly investigate the relationship between specific performance indices and the RMSSD mean and coefficient of variation for female collegiate rowers.
Utilizing a Novel 2D Image Processing System for Relating Body Composition Metrics to Performance in Collegiate Female Rowers
(MDPI, 2021) Esco, Michael R.; Holmes, Clifton J.; Sullivan, Katherine; Hornikel, Bjoern; Fedewa, Michael V.; University of Alabama Tuscaloosa
The purpose of this study was to determine if rowing performance was associated with fat mass (FM) or fat-free mass (FFM) measured using a novel 2D digital image analysis system. Nineteen female rowers (ages = 20.3 +/- 1.0 years, weight = 73.8 +/- 8.3 kg, height = 172.7 +/- 4.7 cm) participated in this study. FM and FFM were estimated with a smartphone application that uses an automated 2D image analysis program. Rowing performance was measured using a 2 km (2k) timed trial on an indoor ergometer. The average speed of the timed trial was recorded in raw units (m center dot s(-1)) and adjusted for body weight (m center dot s(-1)center dot kg(-1)). FFM was significantly correlated to unadjusted 2k speed (r = 0.67, p < 0.05), but not for FM (r = 0.44, p > 0.05). When 2k speed was adjusted to account for body weight, significant correlations were found with FM (r = -0.56, p < 0.05), but not FFM (r = -0.34, p > 0.05). These data indicate that both FM and FFM are related to rowing performance in female athletes, but the significance of the relationships is dependent on overall body mass. In addition, the novel 2D imaging system appears to be a suitable field technique when relating body composition to rowing performance.
Vagally Derived Heart Rate Variability and Training Perturbations With Menses in Female Collegiate Rowers
(Human Kinetics, 2022) Sherman, Sara R.; Holmes, Clifton J.; Demos, Alexander P.; Stone, Tori; Hornikel, Bjoern; MacDonald, Hayley, V; Fedewa, Michael, V; Esco, Michael R.; University of Alabama Tuscaloosa; University of Illinois Chicago; University of Illinois Chicago Hospital; Washington University (WUSTL); Yale University
Introduction: The parasympathetically derived marker of heart rate variability, root mean square of successive R-R differences (RMSSD), and the daily fluctuations as measured by the coefficient of variation (RMSSDCV) may be useful for tracking training adaptations in athletic populations. These vagally derived markers of heart rate variability may be especially pertinent when simultaneously considering a female athlete's menstrual cycle. Purpose: The purpose of this study was to observe the perturbations in RMSSDcv, while considering RMSSD, across a season in the presence and absence of menses with training load in female collegiate rowers. Methods: Thirty-six (20 [1] y, 25.6 [3.4] kg.m(-2)) National Collegiate Athletic Association Division female rowers were monitored for 18 consecutive weeks across a full season. Seated, ultrashortened RMSSD measurements were obtained by the rowers on at least 3 mornings per week using a smartphone photoplethysmography device. Following the RMSSD measurement, athletes indicated the presence or absence of menstruation within the application. Individual meters rowed that week and sessions rate of perceived exertion were obtained to quantify training load. Results: Longitudinal mixedeffects modeling demonstrated a significant effect of menses and time, while also considering RMSSD, such that those who were on their period had a significantly greater RMSSDcv than those who were not (11.2% vs 7.5%, respectively; P < .001). These changes were independent of meters rowed, sessions rate of perceived exertion, body mass index, birth-control use, and years of rowing experience, which were all nonsignificant predictors of RMSSDCgV (P > .05). Conclusion: The presence of menses appears to significantly impact RMSSDCV when also considering RMSSD, which may allow coaches to consider individualized training plans accordingly.
Validity of a 3-compartment body composition model using body volume derived from a novel 2-dimensional image analysis program
(Springer Nature, 2022) Sullivan, Katherine; Hornikel, Bjoern; Holmes, Clifton J.; Esco, Michael R.; Fedewa, Michael V.; University of Alabama Tuscaloosa; Washington University (WUSTL)
Background/Objectives The purpose of this study was: (1) to compare body volume (BV) estimated from a 2-dimensional (2D) image analysis program (BVIMAGE), and a dual-energy x-ray absorptiometry (DXA) equation (BVDXA-Smith-Ryan) to an underwater weighing (UWW) criterion (BVUWW); (2) to compare relative adiposity (%Fat) derived from a 3-compartment (3C) model using BVIMAGE (%Fat(3C-IMAGE)), and a 4-compartment (4C) model using BVDXA-Smith-Ryan (%Fat(4C-DXA-Smith-Ryan)) to a 4C criterion model using BVUWW (%Fat(4C-UWW)). Subject/Methods Forty-eight participants were included (60% male, 22.9 +/- 5.0 years, 24.2 +/- 2.6 kg/m(2)). BVIMAGE was derived using a single digital image of each participant taken from the rear/posterior view. DXA-derived BV was calculated according to Smith-Ryan et al. Bioimpedance spectroscopy and DXA were used to measure total body water and bone mineral content, respectively, in the 3C and 4C models. A standardized mean effect size (ES) assessed the magnitude of differences between models with values of 0.2, 0.5, and 0.8 for small, moderate, and large differences, respectively. Data are presented as mean +/- standard deviation. Results Near-perfect correlation (r = 0.998, p < 0.001) and no mean differences (p = 0.267) were observed between BVIMAGE (69.6 +/- 11.5 L) and BVUWW (69.5 +/- 11.4 L). No mean differences were observed between %Fat(4C-DXA-Smith-Ryan) and the %Fat(4C-UWW) criterion (p = 0.988). Small mean differences were observed between %Fat(3C-IMAGE) and %Fat(4C-UWW) (ES = 0.2, p < 0.001). %Fat(3C-IMAGE) exhibited smaller SEE and TE, and tighter limits of agreement than %Fat(4C-DXA-Smith-Ryan). Conclusions The 2D image analysis program provided an accurate and non-invasive estimate of BV, and subsequently %Fat within a 3C model in generally healthy, young adults.

Browsing by Author "Hornikel, Bjoern"

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