Effect of fasting versus feeding on the bone metabolic response to running

Abstract

Abbreviations: ACa, albumin-adjusted calcium; Bone ALP, bone alkaline phosphatase; BMD, bone mineral density; P-CTX, C-terminal telopeptide region of collagen type 1; CHO, carbohydrate; FAST, overnight fast from 21:00; FED, a standardised breakfast consumed at 08:15; GLP-1, glucagon-like peptide-1; GLP-2, glucagon-like peptide-2; GIP, glucosedependent insulinotropic polypeptide; LMM, linear mixed model; OC, osteocalcin; OPG, osteoprotegerin; P1NP, N-terminal propeptides of procollagen type 1; PTH, parathyroid hormone; PO4, phosphate; RER, respiratory exchange ratio; RPE, ratings of perceived exertion; VO2, oxygen uptake; V02max, maximal rate of oxygen uptake. ABSTRACTIndividuals often perform exercise in the fasted state, but the effects on bone metabolism are not currently known. We compared the effect of an overnight fast with feeding a mixed meal on the bone metabolic response to treadmill running. Ten, physically-active males aged 28 ± 4 y (mean ± 1SD) completed two, counterbalanced, 8 d trials. After 3 d on a standardised diet, participants performed 60 min of treadmill running at 65% V02max on Day 4 following an overnight fast (FAST) or a standardised breakfast (FED). Blood samples were collected at baseline, before and during exercise, for 3h after exercise, and on four consecutive follow-up days (FU1-FU4). Plasma/serum were analysed for the c-terminal telopeptide region of collagen type 1 (P-CTX), n-terminal propeptides of procollagen type 1 (P1NP), osteocalcin (OC), bone alkaline phosphatase (bone ALP), parathyroid hormone (PTH), albumin-adjusted calcium, phosphate, osteoprotegerin (OPG), Cortisol, leptin and ghrelin. Only the P-CTX response was significantly affected by feeding. Pre-exercise concentrations decreased more in FED compared with FAST (47% vs 26%, P < 0.001) but increased during exercise in both groups and were not significantly different from baseline at 1 h post-exercise. At 3 h post-exercise, concentrations were decreased (33%, P < 0.001) from baseline in FAST and significantly lower (P < 0.001) than in FED. P1NP and PTH increased, and OC decreased during exercise. Bone markers were not significantly different from baseline on FU1-FU4.Fasting had only a minor effect on the bone metabolic response to subsequent acute, endurance exercise, reducing the duration of the increase in P-CTX during early recovery, but having no effect on changes in bone formation markers. The reduced duration of the P-CTX response with fasting was not fully explained by changes in PTH, OPQ leptin or ghrelin.

Effect of Recovery Duration between Two Bouts of Running on Bone Metabolism

“…That said, the factors that determine the time course of changes in ß-CTX with endurance exercise remain incompletely understood. For example, ß-CTX increases in the hours after aeute endurance exercise lasting up to 60 min, performed at high exereise intensities including 80% V02max (20), 110% of anaerobic threshold (22), and 115% of ventilatory threshold (VT) (34) but not 85% VT (22), and exereise intensity may be an important factor in this response (22,34,46), It is possible that 65% V02max was not a sufficient intensity to stimulate ß-CTX, With that said, however, we have recently observed a transient increase in ß-CTX after 60 min of running at 65% V02max under identical conditions to those on D5 in SHORT (exercise at 10:30 a.m. in participants fed at 8:00 a.m.) that was no longer evident at 24 h after exercise (47). It is also possible, therefore, that ß-CTX did increase with the exercise bouts, but the response was not sustained through to the following moming.…”

Effects of plyometric exercise session on markers of bone turnover in boys and young men

“…Along these lines, another potential limitation is that while all participants performed exercise in the fed condition, we did not record the specific food intake on the day of exercise. Previous research has demonstrated that feeding (vs. fasting) may acutely suppress bone resorption markers (particularly CTx), although bone formation markers, specifically bone ALP, are generally not affected (Clowes et al 2002;Scott et al 2012). In a study examining the effect of feeding on bone markers in women, Clowes et al (2002) demonstrated an 8.5 % decrease in serum NTx in the fed condition.…”

Effects of fasted vs fed‐state exercise on performance and post‐exercise metabolism: A systematic review and meta‐analysis

“…Six trials determined that glucose was increased in fed conditions following submaximal or prolonged aerobic exercise . The remaining studies indicated glucose was greater in fasted conditions following acute anaerobic or submaximal exercise . Feeding conditions eliciting increases in glucose following exercise compared with fasted conditions included a mixed meal, a glycerol bolus, a carbohydrate‐based meal, an oral carbohydrate solution, and low/high glycaemic index (GI) carbohydrates .…”

“…Feeding conditions eliciting increases in glucose following exercise compared with fasted conditions included a mixed meal, a glycerol bolus, a carbohydrate‐based meal, an oral carbohydrate solution, and low/high glycaemic index (GI) carbohydrates . Conversely, feeding interventions which resulted in lower blood glucose compared with fasting included an oral carbohydrate solution, a glucose bolus, and a mixed meal . Gillen et al observed no differences in oral glucose tolerance responses to 6 weeks of fasted vs fed‐state HIIT.…”