Predicting Adaptations to Resistance Training Plus Overfeeding Using Bayesian Regression: A Preliminary Investigation

Abstract

Relatively few investigations have reported purposeful overfeeding in resistance-trained adults. This preliminary study examined potential predictors of resistance training (RT) adaptations during a period of purposeful overfeeding and RT. Resistance-trained males (n = 28; n = 21 completers) were assigned to 6 weeks of supervised RT and daily consumption of a high-calorie protein/carbohydrate supplement with a target body mass (BM) gain of ≥0.45 kg·wk−1. At baseline and post-intervention, body composition was evaluated via 4-component (4C) model and ultrasonography. Additional assessments of resting metabolism and muscular performance were performed. Accelerometry and automated dietary interviews estimated physical activity levels and nutrient intake before and during the intervention. Bayesian regression methods were employed to examine potential predictors of changes in body composition, muscular performance, and metabolism. A simplified regression model with only rate of BM gain as a predictor was also developed. Increases in 4C whole-body fat-free mass (FFM; (mean ± SD) 4.8 ± 2.6%), muscle thickness (4.5 ± 5.9% for elbow flexors; 7.4 ± 8.4% for knee extensors), and muscular performance were observed in nearly all individuals. However, changes in outcome variables could generally not be predicted with precision. Bayes R2 values for the models ranged from 0.18 to 0.40, and other metrics also indicated relatively poor predictive performance. On average, a BM gain of ~0.55%/week corresponded with a body composition score ((∆FFM/∆BM)*100) of 100, indicative of all BM gained as FFM. However, meaningful variability around this estimate was observed. This study offers insight regarding the complex interactions between the RT stimulus, overfeeding, and putative predictors of RT adaptations.

Offseason Body Composition Changes Detected by Dual-Energy X-ray Absorptiometry versus Multifrequency Bioelectrical Impedance Analysis in Collegiate American Football Athletes

“…While the primary purpose of the study was to simply assess the comparability of DXA and BIA for detecting body composition changes in the context of weight gain, nutritional and dietary supplementation information could have helped further contextualize our results. Nonetheless, the observation of clear increases in BM objectively supports that subjects were in an energy surplus during the study [44], in accordance with our goal. Furthermore, the known problems with accuracy of self-reported energy and nutrient intake often preclude high levels of confidence in these data [45].…”

The influence of caffeinated and non-caffeinated multi-ingredient pre-workout supplements on resistance exercise performance and subjective outcomes

“…Following completion of isometric and isokinetic testing, maximal strength (one repetition maximum; 1RM) and muscular endurance (repetitions to failure; RTF) were assessed via the bench press (BP 1RM ) and leg press (LP 1RM ) exercises. The warmups and weight selection used in the 1RM testing protocol were based on guidelines provided by the National Strength and Conditioning Association as described previously [ 20 ]. Briefly, after completing a series of progressive warmup sets, 1RM attempts were then performed with a goal of obtaining the 1RM within three to five attempts.…”

Tracking changes in body composition: comparison of methods and influence of pre-assessment standardisation

“…A 6-week supervised resistance training (RT) programme was conducted in conjunction with a high-energy diet designed to promote fat-free mass (FFM) accretion (7) . A total of four body composition assessment sessions were performed.…”

“…All participants completed 6 weeks of 3 d/week supervised RT while consuming a hyperenergetic diet as previously described (7)(8)(9) . Briefly, the RT programme was designed by a Certified Strength and Conditioning Specialist and included a lower body session, upper body session and full body session weekly.…”