Christopher J. Womack

Purpose: Verification stages are recommended for maximal oxygen consumption (V̇O _₂max ) determination, but there is currently no standardization of verification stage design. We sought to determine if the length of recovery and the initial intensity of subsequent exercise influence the effectiveness of verification stages during testing for V̇O _₂max . Methods: Twenty-seven participants (20 males, 7 females) completed four graded exercise tests (GXT). Each session included an identical incremental V̇O _₂max (iV̇O _₂max ) protocol, followed by one of four verification stages with combinations of short (5 min) and long (15 min) rest periods, and submaximal (one stage below maximal workload) and supramaximal (one stage above maximal workload) starting intensities. Results: Although iV̇O _₂max and verification V̇O _₂max (vV̇O _₂max ) were similar across all protocols, 11–19% of participants achieved higher values during verification. About 24% of individuals who did not exhibit a V̇O _₂ plateau during the GXT exhibited a vV̇O _₂max > iV̇O _₂max in the submaximal verification protocols compared to 6–14% for the supramaximal protocols. Conclusions: Verification stages using initial submaximal intensities may increase the likelihood of achieving V̇O _₂max .

Article: Body composition measured by multi-frequency bioelectrical impedance following creatine supplementation - The Journal of Sports Medicine and Physical Fitness 2023 Sep 07 - Minerva Medica - Journals

Article: The effect of acute hydration on body composition assessed by multi-frequency and single-frequency bioelectrical impedance - The Journal of Sports Medicine and Physical Fitness 2023 Jun 19 - Minerva Medica - Journals

It is unknown whether oxygen uptake (V̇O₂) sampling intervals influence the efficacy of a verification stage following a graded exercise test (GXT). Fifteen females and 14 males (18–25 years) completed a maximal treadmill GXT. After a 5 ​min recovery, the verification stage began at the speed and grade corresponding with the penultimate stage from the GXT. Maximal oxygen consumption (V̇O_2max) from the incremental GXT (iV̇O_2max) and V̇O_2max from the verification stage (verV̇O_2max) were determined using 10 seconds (s), 30 ​s, and 60 ​s from breath ​× ​breath averages. There was no main effect for V̇O_2max measure (iV̇O_2maxvs. verV̇O_2max) 10 ​s ([47.9 ​± ​8.31] ml∙kg⁻¹∙min⁻¹ vs [48.85 ​± ​7.97] ml∙kg⁻¹∙min⁻¹), 30 ​s ([46.94 ​± ​8.62] ml∙kg⁻¹∙min⁻¹ vs [47.28 ​± ​7.97] ml∙kg⁻¹∙min⁻¹), and 60 ​s ([46.17 ​± ​8.62] ml∙kg⁻¹∙min⁻¹ vs [46.00 ​± ​8.00] ml∙kg⁻¹∙min⁻¹]. There was a stage ​× ​sampling interval interaction as the difference between (verV̇O_2max−iV̇O_2max) was greater for 10-s than 60-s sampling intervals. The verV̇O_2max was > 4% higher than iV̇O_2maxin 31%, 31%, and 17% of the tests for the 10-s, 30-s, and 60-s sampling intervals respectively. Sensitivity for the plateau was < 30% for 10-s, 30-s, and 60-s sampling intervals. Specificity ranged from 44% to 60% for all sampling intervals. Sensitivity for heart rate ​+ ​respiratory exchange ratio was > 90% for all sampling intervals; while specificity was < 25%. Findings from the present study suggest that the efficacy of verification stages for eliciting a higher V̇O_2max may be influenced by the sampling interval utilized.

Article: The influence of the CYP1A2-163 C>A polymorphism on the hemostatic response to exercise following caffeine supplementation - The Journal of Sports Medicine and Physical Fitness 2022 Oct 14 - Minerva Medica - Journals

Background: Because cardiac events are a major cause of in-line deaths in firefighters and caffeine use is common in this population, we sought to examine the effects of caffeine on the hemostatic response to firefighting drills. Materials and Methods: Twelve firefighters completed two trials of firefighting drills after consuming caffeine (6 mg/kg) or placebo. Factor VIII, tissue plasminogen activator (tPA), and plasminogen activator inhibitor-1 (PAI-1) were analyzed from pre- and post-exercise blood samples. Results: Factor VIII increase was larger (p < 0.05) in the caffeine trial (Pre = 0.20 ± 0.13 IU/mL, Post = 0.43 ± 0.15 IU/mL) than the placebo trial (Pre = 0.21 ± 0.11 IU/mL, Post = 0.38 ± 0.15 IU/mL). tPA activity significantly (p < 0.05) increased and PAI-1 activity significantly decreased (p < 0.05) by the same magnitude in both conditions. Conclusions: Results suggest that caffeine elicits a higher coagulation response during firefighting drills.

BACKGROUND: This study investigated the effects of coffee ingestion with supplemental caffeine (CAF) on serum testosterone (T) responses to exercise in recreationally strength-trained males. METHODS: Subjects ingested 6 mg/kg body weight of caffeine via 12 ounces of coffee (CAF) supplemented with anhydrous caffeine or decaffeinated (DEC) coffee prior to exercise in a randomized, within-subject, crossover design. The exercise session consisted of 21 minutes of high-intensity interval cycling (alternating intensities at power outputs associated with 2.0 mmol/L lactate for two minutes and 4.0 mmol/L lactate for one minute) followed by resistance exercise (seven exercises, three sets of ten repetitions, 65% 1RM, one-minute rest periods). Subjects also completed repetitions to fatigue tests and soreness scales to determine muscle recovery 24 hours following the exercise. RESULTS: T was elevated immediately and 30-minutes post-exercise by 20.5% and 143% respectively (P0.05). No relationships were observed between T and any proxy of recovery. CONCLUSIONS: While past literature suggests caffeine may enhance T post-exercise, data from the current study suggest that augmented T response is not evident following anhydrous caffeine added to coffee. The duration of T elevation indicates that this protocol is beneficial to creating long-lasting increases in serum testosterone.

Introduction: Prior studies from our laboratory suggest the −163 C > A polymorphism of the Cytochrome P450 ( CYP1A2 ) gene influences the ergogenic effect of caffeine. However, serum caffeine and/or metabolites have not been reported in these studies. The purpose of this study was to determine whether CYP1A2 polymorphism affects caffeine metabolism and subsequent exercise performance between the genotypes (AA homozygotes and C allele carriers). Material and Methods: Twenty male subjects participated in two 3 km cycling time trials 60 minutes following placebo (all-purpose flour) and caffeine (6 mg/kg BW anhydrous caffeine) supplementation. “Slow metabolizers” were characterized as possessing a C allele (AC heterozygotes and CC homozygotes), and “fast metabolizers” were homozygous for the A allele. Results: C allele carriers had significantly higher serum caffeine after one hour (C allele carriers = 14.2 ± 1.8 ppm, AA homozygotes = 11.7 ± 1.7 ppm, p = 0.001). There were no significant differences ( p > 0.05) between genetic groups for any measured caffeine metabolite, the metabolite:caffeine ratio, or the paraxanthine:caffeine ratio. While there was a main effect ( p = 0.03) for caffeine ingestion on time trial performance, there was no caffeine x genotype interaction (C allele carriers: placebo = 297.0 ± 20.8 seconds, caffeine = 292.0 ± 20.0 seconds; AA homozygotes: placebo = 318.3 ± 34.5 seconds; caffeine = 307.9 ± 21.9 seconds) ( p > 0.05). Conclusions: Results from this study suggest C allele carriers have higher serum caffeine after one hour than AA homozygotes. However, these findings do not support an influence of the CYP1A2 −163 C > A polymorphism on the ergogenic effect of caffeine in a 3 km cycling time trial.

This project was designed to assess the effects of time of day and training status on the benefits of caffeine supplementation for cycling performance. Twenty male subjects (Age, 25 years; Peak oxygen consumption, 57 mL·kg⁻¹·min⁻¹) were divided into tertiles based on training levels, with top and bottom tertiles designated as ‘trained’ (n = 7) and ‘untrained’ (n = 7). Subjects completed two familiarization trials and four experimental trials consisting of a computer-simulated 3-km cycling time trial (TT). The trials were performed in randomized order for each combination of time of day (morning and evening) and treatment (6mg/kg of caffeine or placebo). Magnitude-based inferences were used to evaluate all treatment effects. For all subjects, caffeine enhanced TT performance in the morning (2.3% ± 1.7%, ‘very likely’) and evening (1.4% ± 1.1%, ‘likely’). Both untrained and trained subjects improved performance with caffeine supplementation in the morning (5.5% ± 4.3%, ‘likely’; 1.0% ± 1.7%, ‘likely’, respectively), but only untrained subjects rode faster in the evening (2.9% ± 2.6%, ‘likely’). Altogether, our observations indicate that trained athletes are more likely to derive ergogenic effects from caffeine in the morning than the evening. Further, untrained individuals appear to receive larger gains from caffeine in the evening than their trained counterparts.