Bone resorption is suppressed immediately after the third and fourth days of multiday cycling but persistently increased following overnight recovery

Abstract

Previous studies suggest that seasoned cyclists may incur a low bone mineral density. This study investigated the effect of multiday cycling on bone turnover. Ten male cyclists completed 4 consecutive days of cycling for 3 h·day −1 . Sweat calcium excretion during exercise and serum calcium, cortisol, bone formation marker (bone alkaline phosphotase (bone-ALP)), bone resorptive marker (C-terminal telopeptide of type I collagen (␤-CTX)), and parathyroid hormone concentration were measured before and immediately postexercise each day. Serum ␤-CTX concentration increased from pre-to postcycling on days 1 and 2 (p = 0.01) (day 1: 0.31 ± 0.14 to 0.60 ± 0.4 ng·mL −1 ; day 2: 0.58 ± 0.26 to 0.87 ± 0.42 ng·mL −1 ), while serum bone-ALP concentration remained unchanged. Conversely, on days 3 and 4 both serum ␤-CTX (day 3: 0.60 ± 0.26 to 0.43 ± 0.26 ng·mL −1 , p < 0.05; day 4: 0.63 ± 0.21 to 0.43 ± 0.22 ng·mL −1 , p < 0.001) and bone-ALP (p < 0.01) response to exercise was suppressed. Interestingly, calcium lost to sweat and postexercise serum cortisol concentration were also significantly lower on days 3 and 4 than on day 1 (p < 0.05). However, both serum ␤-CTX (102%-124%) and bone-ALP (25%-29%) remained persistently elevated after 21 h of overnight recovery on all successive days compared with day 1 pre-exercise, where the percentage increase was greater for ␤-CTX (p < 0.05). Bone resorption, immediately following prolonged cycling, is acutely reduced by the third and fourth consecutive days and is coincident to reduced sweat calcium excretion and cortisol concentration. However, multiday cycling imposes a persistent increase in bone resorption following overnight recovery.Key words: bone turnover, bone metabolism, cycling, cortisol, sweat calcium, parathyroid hormone. Résumé :Des études antérieures suggèrent que des cyclistes d'expérience peuvent présenter une faible densité minérale osseuse. Cette étude analyse l'effet de plusieurs jours de vélo sur le renouvellement du tissu osseux. Dix cyclistes masculins participent à 4 jours consécutifs de vélo à raison de 3 h·jour -1 . Tous les jours, avant et immédiatement après l'exercice à vélo, on évalue l'excrétion de calcium dans la sueur au cours de l'exercice ainsi que les variables suivantes : calcium sérique, cortisol, marqueur de la formation osseuse (phosphatase alcaline osseuse (« ALP » osseuse)), marqueur de résorption osseuse (télopeptide c-terminal du collagène de type 1 (« ␤-CTX »)) et concentration de la parathormone. La concentration sérique de ␤-CTX augmente du début à la fin de l'exercice aux jours 1 et 2 (p = 0,01) (jour 1: de 0,31 ± 0,14 à 0,60 ± 0,4 ng·mL -1 ; jour 2: de 0,58 ± 0,26 à 0,87 ± 0,42 ng·mL -1 ), mais la concentration sérique d'ALP osseuse ne varie pas. Par contre, aux jours 3 et 4, la concentration sérique de ␤-CTX (jour 3: de 0,60 ± 0,26 à 0,43 ± 0,26 ng·mL -1 , p < 0,05; jour 4: de 0,63 ± 0,21 à 0,43 ± 0,22 ng·mL -1 , p < 0,001) et d'ALP osseuse (p < 0,01) diminue au cours de l'exercice. Curieusement, la perte de calcium dans la su...

The Effect of Postexercise Carbohydrate and Protein Ingestion on Bone Metabolism

“…Further, unpublished data from our laboratory show that elite triathletes have mean resting bone turnover marker concentrations that are higher than the trained runners and triathletes. This is supported by Oosthuyse et al (25) who showed that bone resorption and bone formation markers were significantly elevated each morning after four successive 3 h cycling bouts in well-trained cyclists. Although this is speculative, elite athletes may experience an imbalance between whole-body rates of resorption and formation or, defective coupling (26), meaning that neither bone resorption or bone formation is performed adequately and the quality of the bone may be poorer.…”

“…Although this increased bone turnover response may be positive in sub-elite populations, elite athletes that train multiple times a day with minimal recovery time and rest days are more likely to suffer from consistently increased bone remodelling, which may have detrimental effects on bone health and enhance the stress fracture risk (25,26,28,30). The trained runners and triathletes in the present study have mean resting bone turnover marker concentrations that are at the upper end of the reference ranges for the non-active, healthy population (7,11,12).…”

Dietary-Lifestyle Patterns Associated with Bone Turnover Markers, and Bone Mineral Density in Adult Male Distance Amateur Runners—A Cross-Sectional Study

“…This bone turnover marker is related to bone resorption, and some studies suggest that it is one of the least influenced by intensive physical exercise bone turnover markers [ 3 , 33 ]. On the contrary, there are studies that show that aerobic exercise bouts increase cTX in male triathletes [ 34 ].…”

Comparison of energy supplements during prolonged exercise for maintenance of cardiac function: carbohydrate only versus carbohydrate plus whey or casein hydrolysate

“…Fluid retention (L) = ingested fluid volume -urine volume -sweat loss Sweat loss was calculated according to the equations of Cheuvront et al (2007) as the change in body mass from pre to post exercise plus the volume of fluid ingested minus the volume of urine excreted, and minus respiratory water loss and CO 2 /O 2 exchange measured by indirect calorimetry, as described previously (Oosthuyse et al 2014).…”