Comparing Acute, High Dietary Protein and Carbohydrate Intake on Transcriptional Biomarkers, Fuel Utilisation and Exercise Performance in Trained Male Runners

Abstract

Manipulating dietary macronutrient intake may modulate adaptive responses to exercise, and improve endurance performance. However, there is controversy as to the impact of short-term dietary modification on athletic performance. In a parallel-groups, repeated measures study, 16 trained endurance runners (maximal oxygen uptake (V˙O2max): 64.2 ± 5.6 mL·kg−1·min−1) were randomly assigned to, and provided with, either a high-protein, reduced-carbohydrate (PRO) or a high-carbohydrate (CHO) isocaloric-matched diet. Participants maintained their training load over 21-consecutive days with dietary intake consisting of 7-days habitual intake (T1), 7-days intervention diet (T2) and 7-days return to habitual intake (T3). Following each 7-day dietary period (T1–T3), a micro-muscle biopsy was taken for assessment of gene expression, before participants underwent laboratory assessment of a 10 km treadmill run at 75% V˙O2max, n treadmill run at 70% vV˙O2max time to exhaustion (TTE) trial. The PRO diet resulted in a modest change (1.37-fold increase, p = 0.016) in AMPK expression, coupled with a significant increase in fat oxidation (0.29 ± 0.05 to 0.59 ± 0.05 g·min−1, p < 0.0001). However, a significant reduction of 23.3% (p = 0.0003) in TTE post intervention was observed; this reverted back to pre levels following a return to the habitual diet. In the CHO group, whilst no change in sub-maximal fuel utilisation occurred at T2, a significant 6.5% increase in TTE performance (p = 0.05), and a modest, but significant, increase in AMPK (p = 0.042) and PPAR (p = 0.029) mRNA expression compared to T1 were observed; with AMPK (p = 0.011) and PPAR (p = 0.044) remaining significantly elevated at T3. In conclusion, a 7-day isocaloric high protein diet significantly compromised high intensity exercise performance in trained runners with no real benefit on gene markers of training adaptation. A significant increase in fat oxidation during submaximal exercise was observed post PRO intervention, but this returned to pre levels once the habitual diet was re-introduced, suggesting that the response was driven via fuel availability rather than cellular adaptation. A short-term high protein, low carbohydrate diet in combination with endurance training is not preferential for endurance running performance.

The efficacy of a home-use metabolic device (Lumen) in response to a short-term low and high carbohydrate diet in healthy volunteers

“…Our findings support previous research [ 32 ] that the device detects acute changes in L%CO 2 following a significant increase in carbohydrate intake, and collectively these results demonstrate that the Lumen device could have pertinent applications in non-invasively monitoring response to acute meal settings (e.g. pre-exercise carbohydrate strategies) considering previous research highlighting the association between carbohydrate oxidation and exercise performance [ 18 , 38 , 54–56 ].…”

“…From this initial habituation period (NORM), individual maintenance caloric intake was determined based on predicted basal metabolic rate (using the Harris-Benedict formula), adjusted against habitual training demands and estimated non-exercise activity thermogenesis [ 38 ]. Participants were randomly assigned a 7-day dietary intervention comprising either isocaloric low-carbohydrate (LOW) intake (target ratio of ~20–25% EI from carbohydrate, 15–20% protein, 55–60% fat) or isocaloric high-carbohydrate (HIGH) intake (target ratio ~55–60% EI from carbohydrate, 15–20% protein, 20–25% fat).…”

Gut Microbial Stability is Associated with Greater Endurance Performance in Athletes Undertaking Dietary Periodization

“…1 , expressed as relative change (%) from preintervention baseline. Further detail on the impact of the dietary intervention on performance has been previously reported ( 29 ). Following HPD, time trial to exhaustion (TTE) was reduced within group by −23.3% midintervention, with all participants exhibiting decreased ability to perform ( P < 0.001).…”

“…7 ). Participants were requested to maintain training regimes throughout the duration of the study as previously reported ( 29 ).…”