This study investigated the effect of the racemic β-hydroxybutyrate (βHB) precursor, R,S-1,3-butanediol (BD), on time-trial (TT) performance and tolerability. A repeated-measures, randomized, crossover study was conducted in nine trained male cyclists (age, 26.7 ± 5.2 years; body mass, 69.6 ± 8.4 kg; height, 1.82 ± 0.09 m; body mass index, 21.2 ± 1.5 kg/m2; VO2peak,63.9 ± 2.5 ml·kg−1·min−1; W max, 389.3 ± 50.4 W). Participants ingested 0.35 g/kg of BD or placebo 30 min before and 60 min during 85 min of steady-state exercise, which preceded a ∼25- to 35-min TT (i.e., 7 kJ/kg). The ingestion of BD increased blood D-βHB concentration throughout exercise (0.44–0.79 mmol/L) compared with placebo (0.11–0.16 mmol/L; all p < .001), which peaked 1 hr following the TT (1.38 ± 0.35 vs. 0.34 ± 0.24 mmol/L; p < .001). Serum glucose and blood lactate concentrations were not different between trials (all p > .05). BD ingestion increased oxygen consumption and carbon dioxide production after 20 min of steady-state exercise (p = .002 and p = .032, respectively); however, no further effects on cardiorespiratory parameters were observed. Within the BD trial, moderate to severe gastrointestinal symptoms were reported in five participants, and low levels of dizziness, nausea, and euphoria were reported in two participants. However, this had no effect on TT duration (placebo, 28.5 ± 3.6 min; BD, 28.7 ± 3.2 min; p = .62) and average power output (placebo, 290.1 ± 53.7 W; BD, 286.4 ± 45.9 W; p = .50). These results suggest that BD has no benefit for endurance performance.
David M. Shaw, Fabrice Merien, Andrea Braakhuis, Daniel Plews, Paul Laursen and Deborah K. Dulson
Ralph Beneke and Renate M. Leithäuser
Bryan McCullick and Mark Byra
Jos J. de Koning and Dionne A. Noordhof
Patellar tendinopathy is one of the most common afflictions in jumping sports. This case study outlines the rehabilitation of a professional basketball player diagnosed by magnetic resonance imaging (MRI) with a central core patellar tendinopathy within the proximal enthesis. The player undertook a nutrition and strength-based rehabilitation program combining gelatin ingestion and heavy isometric loading of the patellar tendon designed to produce significant stress relaxation as part of their competition schedule and a whole-body training plan. On follow-up one and a half years into the program an independent orthopedic surgeon declared the tendon normal on MRI. Importantly, the improved MRI results were associated with a decrease in pain and improved performance. This case study provides evidence that a nutritional intervention combined with a rehabilitation program that uses stress relaxation can improve clinical outcomes in elite athletes.
Edgar J. Gallardo and Andrew R. Coggan
Consumption of beetroot juice (BRJ) supplements has become popular among athletes because beets tend to be rich in nitrate (NO3−), which can enhance exercise performance by increasing nitric oxide production. The NO3− content of beets can vary significantly, however, making it difficult to know how much NO3− any product actually contains. Samples from 45 different lots of 24 different BRJ products from 21 different companies were therefore analyzed for NO3− (and nitrite [NO2−]) concentration using high-performance liquid chromatography. The NO3− and NO2− content (i.e., amount per serving) was then calculated based on either (a) the manufacturer’s recommended serving size (for prepackaged/single dose products) or (b) as used in previous studies, a volume of 500 ml (for BRJ sold in bulk containers). There was moderate-to-large variability in NO3− content between samples of the same product, with a mean coefficient of variation of 30% ± 26% (range 2–83%). There was even greater variability between products, with a ∼50-fold range in NO3− content between the lowest and highest. Only five products consistently provided ≥5 mmol of NO3−/serving, which seems to be the minimal dose required to enhance exercise performance in most individuals. NO2− contents were generally low (i.e., ≤0.5% compared with NO3−), although two products contained 10% and 14%. The results of this study may be useful to athletes and their support staff contemplating which (if any) BRJ product to utilize. These data may also offer insight into variability in the literature with respect to the effects of BRJ on exercise performance.