Bone and energy metabolism parameters in professional cyclists during the Giro d'Italia 3-weeks stage race

Mapping the complexities of Relative Energy Deficiency in Sport (REDs): development of a physiological model by a subgroup of the International Olympic Committee (IOC) Consensus on REDs

The 2023 International Olympic Committee (IOC) consensus statement on Relative Energy Deficiency in Sport (REDs) notes that exposure to low energy availability (LEA) exists on a continuum between adaptable and problematic LEA, with a range of potential effects on both health and performance. However, there is variability in the outcomes of LEA exposure between and among individuals as well as the specific manifestations of REDs. We outline a framework for a 'systems biology' examination of the effect of LEA on individual body systems, with the eventual goal of creating an integrated map of body system interactions. We provide a template that systematically identifies characteristics of LEA exposure (eg, magnitude, duration, origin) and a variety of moderating factors (eg, medical history, diet and training characteristics) that could exacerbate or attenuate the type and severity of impairments to health and performance faced by an individual athlete. The REDs Physiological Model may assist the diagnosis of underlying causes of problems associated with LEA, with a personalised and nuanced treatment plan promoting compliance and treatment efficacy. It could also be used in the strategic prevention of REDs by drawing attention to scenarios of LEA in which impairments of health and performance are most likely, based on knowledge of the characteristics of the LEA exposure or moderating factors that may increase the risk of harmful outcomes. We challenge researchers and practitioners to create a unifying and dynamic physiological model for each body system that can be continuously updated and mapped as knowledge is gained.

One Season in Professional Cycling Is Enough to Negatively Affect Bone Health

Cycling is a very popular sport worldwide, and several studies have already indicated that cycling at various levels has a negative impact on bone health. This is of concern to both performance and health managers of many cycling teams at different levels because of its economic and social impact. Based on the scientific literature, we hypothesize that a single season at the professional level can negatively affect bone health status. The aim of this study was to assess how professional cycling affects bone health markers after one season. Densitometry was used to measure the bone mineral density (BMD), bone mineral content (BMC), bone area (BA), fat mass (FM), fat-free mass (FFM), T-score and Z-score in professional cyclists after one season. After one season at the professional level, cyclists' BMD decreased significantly in the legs, trunk, ribs and pelvis (p ≤ 0.05). BMC decreased in the arms and spine (p ≤ 0.05). BA decreased significantly in the arms and spine (p ≤ 0.05). In addition, a significant decrease in Z-score (p ≤ 0.05) and a decreasing trend in T-score and total BMD (p = 0.06) were observed. One season of professional cycling is enough to negatively affect bone health status.

Effect of increased protein intake and exogenous ketosis on body composition, energy expenditure and exercise capacity during a hypocaloric diet in recreational female athletes

Introduction: Since low body weight is an important determinant of success in many sports such as gymnastics, martial arts and figure skating, athletes can benefit from effective weight loss strategies that preserve muscle mass and athletic performance. The present study investigates the effects of increased protein intake and exogenous ketosis on body composition, energy expenditure, exercise capacity, and perceptions of appetite and well-being during a hypocaloric diet in females. Methods: Thirty-two female recreational athletes (age: 22.2 ± .5 years; body weight: 58.3 ± .8 kg; BMI: 20.8 ± .2 kg·m^-2) underwent 4 weeks of 30% caloric restriction and were randomized to receive either an increased daily amount of dietary protein (PROT, ∼2.0-2.2 g protein·kg^-1·day^-1), 3 × 20 g·day^-1 of a ketone ester (KE), or an isocaloric placebo (PLA). Body composition was measured by DXA, resting energy expenditure (REE) by indirect calorimetry, exercise capacity during a VO₂max test, appetite hormones were measured in serum, and perceptions of general well-being were evaluated via questionnaires. Results: The hypocaloric diet reduced body weight by 3.8 ± .3 kg in PLA, 3.2 ± .3 kg in KE and 2.4 ± .2 kg in PROT (P_time<.0001). The drop in fat mass was similar between treatments (average: 2.6 ± .1 kg, P_time<.0001), while muscle mass was only reduced in PLA and KE (average: .8 ± .2 kg, P_time<.05), and remained preserved in PROT (P_interaction<.01). REE [adjusted for lean mass] was reduced after caloric restriction in PLA (pre: 32.7 ± .5, post: 28.5 ± .6 kcal·day^-1·kg^-1) and PROT (pre: 32.9 ± 1.0, post: 28.4 ± 1.0 kcal·day^-1·kg^-1), but not in KE (pre: 31.8 ± .9, post: 30.4 ± .8 kcal·day^-1·kg^-1) (P_interaction<.005). Furthermore, time to exhaustion during the VO₂max test decreased in PLA (by 2.5 ± .7%, p < .05) but not in KE and PROT (P_interaction<.05). Lastly, the perception of overall stress increased in PLA and PROT (p < .05), but not in KE (P_interaction<.05). Conclusion: Increased protein intake effectively prevented muscle wasting and maintained exercise capacity during a period of caloric restriction in female recreational athletes. Furthermore, exogenous ketosis did not affect body composition, but showed its potential in weight management by preserving a drop in exercise capacity and REE and by improving overall stress parameters during a period of caloric restriction.

Positive association of glucagon with bone turnover markers in type 2 diabetes: A cross-sectional study

AIMS

The osteo-metabolic changes in type 2 diabetes (T2D) patients are intricate and have not been fully revealed. It is not clear whether glucagon is entirely harmful in the pathogenesis of diabetes or a possible endocrine counter-regulation mechanism to reverse some abnormal bone metabolism. This study aimed to investigate the association between glucagon and bone turnover markers (BTMs) in T2D patients.

METHODS

A total of 3984 T2D participants were involved in a cross-sectional study in Shanghai, China. Serum glucagon was measured to elucidate its associations with intact N-terminal propeptide of type I collagen (P1NP), osteocalcin (OC), and β-C-terminal telopeptide (β-CTX). Glucagon was detected with a radioimmunoassay. Propeptide of type I collagen, OC, and β-CTX were detected using chemiluminescence. The diagnosis of T2D was based on American Diabetes Association criteria.

RESULTS

The concentration of glucagon was positively correlated with two BTMs [OC-β: 0.034, 95% CI: 0.004, 0.051, p = 0.024; CTX-β: 0.035, 95% CI: 0.004, 0.062, p = 0.024]. The result of P1NP was [P1NP-regression coefficient (β): 0.027, 95% CI: -0.003, 0.049, p = 0.083]. In the glucagon tertiles, P for trend of the BTMs is [P1NP: 0.031; OC: 0.038; CTX: 0.020], respectively.

CONCLUSIONS

Glucagon had a positive effect on bone metabolism. The concentrations of the three BTMs increased as glucagon concentrations rose. This implied that glucagon might speed up skeletal remodelling, accelerate osteogenesis, and promote the formation of mature bone tissue. At the same time, the osteoclastic process was also accelerated, providing raw materials for osteogenesis to preserve the dynamic balance. In view of the successful use of single-molecule as well as dual/triple agonists, it would be feasible to develop a preparation that would reduce osteoporosis in diabetic patients.

Professional cyclists have lower levels of bone markers than amateurs. Is there a risk of osteoporosis in cyclist?

Currently, there is a greater number of amateurs that practice cycling. However, there is no clear evidence regarding bone health in amateur cyclists compared to professional cyclists, as the latter has shown to have lower bone mineral content and density. Therefore, the aim of this study was to identify the differences in bone variables between professional (PRO) and amateur (AMA) road cyclists, and to see if these differences were related to differences in cycling performance. A parallel trial was carried out with 15 AMA and 10 PRO cyclists. All cyclists visited the laboratory twice: 1) in a fasted state, body composition measured by dual-energy X-ray absorptiometry (DXA) and 2) physiological variables measured using an incremental test until exhaustion. Significantly lower values were found in bone mineral density, bone mineral content and fat free mass in PRO compared to AMA (p < 0.05). In addition, significantly higher power was produced in ventilatory thresholds 1 and 2 (VT1 and VT2) and VO_2MAX in PRO compared to AMA (p < 0.05). Overall, PRO cyclists had lower values in bone health and muscle mass but better results in performance compared to AMA.

Bone-to-Brain: A Round Trip in the Adaptation to Mechanical Stimuli

Besides the classical ones (support/protection, hematopoiesis, storage for calcium, and phosphate) multiple roles emerged for bone tissue, definitively making it an organ. Particularly, the endocrine function, and in more general terms, the capability to sense and integrate different stimuli and to send signals to other tissues, has highlighted the importance of bone in homeostasis. Bone is highly innervated and hosts all nervous system branches; bone cells are sensitive to most of neurotransmitters, neuropeptides, and neurohormones that directly affect their metabolic activity and sensitivity to mechanical stimuli. Indeed, bone is the principal mechanosensitive organ. Thanks to the mechanosensing resident cells, and particularly osteocytes, mechanical stimulation induces metabolic responses in bone forming (osteoblasts) and bone resorbing (osteoclasts) cells that allow the adaptation of the affected bony segment to the changing environment. Once stimulated, bone cells express and secrete, or liberate from the entrapping matrix, several mediators (osteokines) that induce responses on distant targets. Brain is a target of some of these mediator [e.g., osteocalcin, lipocalin2, sclerostin, Dickkopf-related protein 1 (Dkk1), and fibroblast growth factor 23], as most of them can cross the blood-brain barrier. For others, a role in brain has been hypothesized, but not yet demonstrated. As exercise effectively modifies the release and the circulating levels of these osteokines, it has been hypothesized that some of the beneficial effects of exercise on brain functions may be associated to such a bone-to-brain communication. This hypothesis hides an interesting clinical clue: may well-addressed physical activities support the treatment of neurodegenerative diseases, such as Alzheimer’s and Parkinson’s diseases?

Mountain Bike Racing Stimulates Osteogenic Bone Signaling and Ingesting Carbohydrate-Protein Compared With Carbohydrate-Only Prevents Acute Recovery Bone Resorption Dominance

ABSTRACT

Oosthuyse, T, Bosch, AN, Kariem, N, and Millen, AME. Mountain bike racing stimulates osteogenic bone signaling and ingesting carbohydrate-protein compared with carbohydrate-only prevents acute recovery bone resorption dominance. J Strength Cond Res 35(2): 292-299, 2021-Mountain biking, unlike road cycling, includes vibrational accelerations but whether it stimulates osteogenic signaling remains unknown. Furthermore, exercise nutrition influences bone turnover, and the effect of ingesting protein during multiday racing was investigated. We measured plasma bone turnover markers, C-terminal telopeptide of type1-collagen (β-CTX) and N-terminal propeptides of type1-procollagen (P1NP), and osteocyte mechanosensory signaling factor, sclerostin (SOST), corrected for plasma volume change, before (pre-day 1) and 20-60 minutes after (post-day 3) a multiday mountain bike race in 18 male cyclists randomly assigned to ingest carbohydrate-only (CHO-only) or carbohydrate-with-casein protein hydrolysate (CHO-PRO) during racing. Fourteen cyclists (n = 7 per group) completed the race, and data were analyzed with p < 0.05 accepted as significant. Plasma SOST decreased similarly in both groups (mean ± SD, CHO-only: 877 ± 451 to 628 ± 473 pg·ml-1, p = 0.004; CHO-PRO: 888 ± 411 to 650 ± 443 pg·ml-1, p = 0.003), suggesting that osteocytes sense mountain biking as mechanical loading. However, the bone formation marker, P1NP, remained unchanged in both groups, whereas the bone resorption marker, β-CTX, increased in CHO-only (0.19 ± 0.034 to 0.31 ± 0.074 ng·ml-1, p = 0.0036) but remained unchanged in CHO-PRO (0.25 ± 0.079 to 0.26 ± 0.074 ng·ml-1, p = 0.95). Mountain bike racing does stimulate osteogenic bone signaling but bone formation is not increased acutely after multiday mountain biking; investigation for a delayed effect is warranted. The acute recovery increase in bone resorption with CHO-only is prevented by ingesting CHO-PRO during racing.

Acute moderate-intensity exercise increases total antioxidant capacity and anti-inflammatory responses in competitive cyclists: The role of adiponectin

High-intensity exercise can elicit acute changes in the biochemical and physiological processes in the body of an athlete, including increased oxidative stress and inflammation. The purpose of this study was to explore the effect of acute moderate-intensity exercise on total antioxidant capacity (TAC) and serum levels of anti-inflammatory adiponectin (APN), and inflammatory markers in competitive cyclists. Ten male cyclists (age 15–26 years, body mass index 19.4–24.7 kg/m2) participated in this study. Each subject performed the maximal oxygen uptake test (VO2peak) and completed a 10-min cycling exercise at a workload of 50% of the peak of VO2peak. Blood samples were collected on three different occasions: after an overnight fasting and at the exercise workloads of 50% and 100% VO2peak. We measured APN, TAC, inflammatory markers as well as assessed nutrient and energy intake for each participant. Baseline concentration of serum APN (10.92 µg/mL) significantly increased at 50% and at 100% VO2peak. In addition, TAC also increased after acute exercise (0.079 vs 0.093 nmol/µL). The concentration of APN at 50% VO2peak positively correlated with the CRP ( r = 0.640, p = 0.046) and negatively correlated with TNF-α ( r = −0.696, p = 0.025). This test showed that short (10 min) and medium-intensity (50% VO2peak) exercise activity in trained athletes evoked beneficial antioxidant and anti-inflammatory responses. Importantly, this response correlates with the increase in APN levels thereby showing that highly trained individuals have beneficial responses originating from adipose tissue. Our observations show that a short training at moderate activity can be an important preservative strategy during the recovery training period.

Laboratory medicine: health evaluation in elite athletes

The need to evaluate the health status of an athlete represents a crucial aim in preventive and protective sports science in order to identify the best diagnostic strategy to improve performance and reduce risks related to physical exercise. In the present review we aim to define the main biochemical and haematological markers that vary significantly during and after sports training to identify risk factors, at competitive and professional levels and to highlight the set up of a specific parameter's panel for elite athletes. Moreover, we also intend to consider additional biomarkers, still under investigation, which could further contribute to laboratory sports medicine and provide reliable data that can be used by athlete's competent staff in order to establish personal attitudes and prevent sports injuries.

Physical Activity-Dependent Regulation of Parathyroid Hormone and Calcium-Phosphorous Metabolism

Exercise perturbs homeostasis, alters the levels of circulating mediators and hormones, and increases the demand by skeletal muscles and other vital organs for energy substrates. Exercise also affects bone and mineral metabolism, particularly calcium and phosphate, both of which are essential for muscle contraction, neuromuscular signaling, biosynthesis of adenosine triphosphate (ATP), and other energy substrates. Parathyroid hormone (PTH) is involved in the regulation of calcium and phosphate homeostasis. Understanding the effects of exercise on PTH secretion is fundamental for appreciating how the body adapts to exercise. Altered PTH metabolism underlies hyperparathyroidism and hypoparathyroidism, the complications of which affect the organs involved in calcium and phosphorous metabolism (bone and kidney) and other body systems as well. Exercise affects PTH expression and secretion by altering the circulating levels of calcium and phosphate. In turn, PTH responds directly to exercise and exercise-induced myokines. Here, we review the main concepts of the regulation of PTH expression and secretion under physiological conditions, in acute and chronic exercise, and in relation to PTH-related disorders.

Ketone ester supplementation blunts overreaching symptoms during endurance training overload

KEY POINTS

Overload training is required for sustained performance gain in athletes (functional overreaching). However, excess overload may result in a catabolic state which causes performance decrements for weeks (non-functional overreaching) up to months (overtraining). Blood ketone bodies can attenuate training- or fasting-induced catabolic events. Therefore, we investigated whether increasing blood ketone levels by oral ketone ester (KE) intake can protect against endurance training-induced overreaching. We show for the first time that KE intake following exercise markedly blunts the development of physiological symptoms indicating overreaching, and at the same time significantly enhances endurance exercise performance. We provide preliminary data to indicate that growth differentiation factor 15 (GDF15) may be a relevant hormonal marker to diagnose the development of overtraining. Collectively, our data indicate that ketone ester intake is a potent nutritional strategy to prevent the development of non-functional overreaching and to stimulate endurance exercise performance.

ABSTRACT

It is well known that elevated blood ketones attenuate net muscle protein breakdown, as well as negate catabolic events, during energy deficit. Therefore, we hypothesized that oral ketones can blunt endurance training-induced overreaching. Fit male subjects participated in two daily training sessions (3 weeks, 6 days/week) while receiving either a ketone ester (KE, n = 9) or a control drink (CON, n = 9) following each session. Sustainable training load in week 3 as well as power output in the final 30 min of a 2-h standardized endurance session were 15% higher in KE than in CON (both P < 0.05). KE inhibited the training-induced increase in nocturnal adrenaline (P < 0.01) and noradrenaline (P < 0.01) excretion, as well as blunted the decrease in resting (CON: -6 ± 2 bpm; KE: +2 ± 3 bpm, P < 0.05), submaximal (CON: -15 ± 3 bpm; KE: -7 ± 2 bpm, P < 0.05) and maximal (CON: -17 ± 2 bpm; KE: -10 ± 2 bpm, P < 0.01) heart rate. Energy balance during the training period spontaneously turned negative in CON (-2135 kJ/day), but not in KE (+198 kJ/day). The training consistently increased growth differentiation factor 15 (GDF15), but ∼2-fold more in CON than in KE (P < 0.05). In addition, delta GDF15 correlated with the training-induced drop in maximal heart rate (r = 0.60, P < 0.001) and decrease in osteocalcin (r = 0.61, P < 0.01). Other measurements such as blood ACTH, cortisol, IL-6, leptin, ghrelin and lymphocyte count, and muscle glycogen content did not differentiate KE from CON. In conclusion, KE during strenuous endurance training attenuates the development of overreaching. We also identify GDF15 as a possible marker of overtraining.

Effects of different training modalities on phosphate homeostasis and local vitamin D metabolism in rat bone

Objectives

Mechanical loading may be an important factor in the regulation of bone derived hormones involved in phosphate homeostasis. This study investigated the effects of peak power and endurance training on expression levels of fibroblast growth factor 23 (FGF23) and 1α-hydroxylase (CYP27b1) in bone.

Methods

Thirty-eight rats were assigned to six weeks of training in four groups: peak power (PT), endurance (ET), PT followed by ET (PET) or no training (control). In cortical bone, FGF23 was quantified using immunohistochemistry. mRNA expression levels of proteins involved in phosphate and vitamin D homeostasis were quantified in cortical bone and kidney. C-terminal FGF23, 25-hydroxyvitamin D3, parathyroid hormone (PTH), calcium and phosphate concentrations were measured in plasma or serum.

Results

Neither FGF23 mRNA and protein expression levels in cortical bone nor FGF23 plasma concentrations differed between the groups. In cortical bone, mRNA expression levels of sclerostin (SOST), dental matrix protein 1 (DMP1), phosphate-regulating gene with homologies to endopeptidases on the X chromosome (PHEX) and matrix extracellular phosphoglycoprotein (MEPE) were lower after PT compared to ET and PET. Expression levels of CYP27b1 and vitamin D receptor (VDR) in tibial bone were decreased after PT compared to ET. In kidney, no differences between groups were observed for mRNA expression levels of CYP27b1, 24-hydroxylase (CYP24), VDR, NaPi-IIa cotransporter (NPT2a) and NaPi-IIc cotransporter (NPT2c). Serum PTH concentrations were higher after PT compared to controls.

Conclusion

After six weeks, none of the training modalities induced changes in FGF23 expression levels. However, PT might have caused changes in local phosphate regulation within bone compared to ET and PET. CYP27b1 and VDR expression in bone was reduced after PT compared to ET, suggesting high intensity peak power training in this rat model is associated with decreased vitamin D signalling in bone.

Physical Activity and Bone Health: What Is the Role of Immune System? A Narrative Review of the Third Way

Bone tissue can be seen as a physiological hub of several stimuli of different origin (e.g., dietary, endocrine, nervous, immune, skeletal muscle traction, biomechanical load). Their integration, at the bone level, results in: (i) changes in mineral and protein composition and microarchitecture and, consequently, in shape and strength; (ii) modulation of calcium and phosphorous release into the bloodstream, (iii) expression and release of hormones and mediators able to communicate the current bone status to the rest of the body. Different stimuli are able to act on either one or, as usual, more levels. Physical activity is the key stimulus for bone metabolism acting in two ways: through the biomechanical load which resolves into a direct stimulation of the segment(s) involved and through an indirect load mediated by muscle traction onto the bone, which is the main physiological stimulus for bone formation, and the endocrine stimulation which causes homeostatic adaptation. The third way, in which physical activity is able to modify bone functions, passes through the immune system. It is known that immune function is modulated by physical activity; however, two recent insights have shed new light on this modulation. The first relies on the discovery of inflammasomes, receptors/sensors of the innate immunity that regulate caspase-1 activation and are, hence, the tissue triggers of inflammation in response to infections and/or stressors. The second relies on the ability of certain tissues, and particularly skeletal muscle and adipose tissue, to synthesize and secrete mediators (namely, myokines and adipokines) able to affect, profoundly, the immune function. Physical activity is known to act on both these mechanisms and, hence, its effects on bone are also mediated by the immune system activation. Indeed, that immune system and bone are tightly connected and inflammation is pivotal in determining the bone metabolic status is well-known. The aim of this narrative review is to give a complete view of the exercise-dependent immune system-mediated effects on bone metabolism and function.

Relative Energy Deficiency in Sport in Male Athletes: A Commentary on Its Presentation Among Selected Groups of Male Athletes

Low energy availability (LEA) is a key element of the Female Athlete Triad. Causes of LEA include failure to match high exercise energy expenditure (unintentional) or pathological behaviors of disordered eating (compulsive) and overzealous weight control programs (misguided but intentional). Recognition of such scenarios in male athletes contributed to the pronouncement of the more inclusive Relative Energy Deficiency in Sport (RED-S) syndrome. This commentary describes the insights and experience of the current group of authors around the apparently heightened risk of LEA in some populations of male athletes: road cyclists, rowers (lightweight and open weight), athletes in combat sports, distance runners, and jockeys. The frequency, duration, and magnitude of the LEA state appear to vary between populations. Common risk factors include cyclical management of challenging body mass and composition targets (including "making weight") and the high energy cost of some training programs or events that is not easily matched by energy intake. However, additional factors such as food insecurity and lack of finances may also contribute to impaired nutrition in some populations. Collectively, these insights substantiate the concept of RED-S in male athletes and suggest that a specific understanding of a sport, subpopulation, or culture may identify a complex series of factors that can contribute to LEA and the type and severity of its outcomes. This commentary provides a perspective on the range of risk factors that should be addressed in future surveys of RED-S in athletic populations and targeted for specific investigation and modification.

Effects of repeated sprints training on fracture risk-associated miRNA

Repeated-sprint training (RS, short-duration sprints at supramaximal intensities interspersed with brief recoveries) is a time-saving metabolically effective strategy whose effects on bone are unknown. Bone metabolism is a finely regulated process profoundly affected by exercise as assayable by studying specific systemic (e.g., hormones, cytokines) and bone-derived molecules (e.g., bone markers, miRNAs). Aim of this study was to determine the effect of a 8-week repeated-sprint on circulating levels of fracture risk-associated miRNA. Blood was collected from 9 subjects performing RS 3 times/week (EXP) and 9 age-matched inactive controls (CTRL) before the start of the protocol (T0) and after 4 (T1) and 8 weeks (T2). The relative expression of miR-21-5p, miR-23a-3p, miR-24-3p, miR93-5p, miR-100-5p, miR-122-5p, miR-124-3p, miR-125b-5p, miR-148a-3p, miR-637 was assayed by real-time PCR by the 2^−ΔΔCT method (housekeeping: miR-425-5p, miR-484). Serum concentrations of bone markers (DKK1, sclerostin, osteoprotegerin, osteocalcin, osteopontin), cytokines (IL-1β, TNFα), and metabolic hormones (leptin, insulin, PTH) were assayed by multiplex assay. miR-637 and miR-124-3p were undetectable. In CTRL miRNA levels remained unchanged. In EXP miR-21-5p remained unchanged. Compared to T0 miR-23a-3p and miR-24-3p were significantly decreased at T1 and T2, also compared to CTRL, miR-100 was significantly decreased at T2, miR-122-5p, miR-125-5p, and miR148a-3p were significantly decreased at T1, while miR-93-5p was significantly increased at T1. None of the metabolic hormones was affected by the intervention while, among the bone markers, DKK1, osteocalcin and sclerostin were slightly but significantly decreased. In conclusion, an 8-week repeated-sprint training downregulates the expression of circulating miRNA associated with fracture risk.

Urinary Steroid Profile in Ironman Triathletes

The aim of this study was to determine variations in the urinary steroid profile of triathletes following an Ironman event. A total of 10 male participants (age = 36.0 ± 1.27 years; body height = 179.29 ± 10.77 cm; body mass = 74.50 ± 1.04 kg) completed an Ironman Championship. Urine samples were collected before, immediately after, and 24 hours following the race. Gas chromatography-mass spectrometry (GC/MS) was used to detect and quantify catabolic and anabolic hormones: Androsterone, Dehydroepiandrosteone (DHEA), Androstenedione and Testosterone (T), Betaestradiol, Estrone, Progesterone, Cortisol (C), Cortisone, Tetrahydrocortisol (THE) and Tetrahydrocortisone (THF). These were measured in their glucuroconjugated and free forms. Androsterone (3297.80 ± 756.83 vs. 2154.26 ± 1375.38), DHEA (47.80 ± 19.21 vs. 32.62 ± 15.96) and Beta-estradiol (59.36 ± 11.7 vs. 41.67 ± 10.59) levels decreased after the event. The significant decrease of DHEA (47.80 ± 19.21 vs. 32.11 ± 14.03) remained at 24 hours. Cortisol (200.38 ± 56.60 vs. 257.10 ± 74.00) and THE (238.65 ± 81.55 vs. 289.62 ± 77.13) increased after exercise and remained elevated 24 hours later (200.38 ± 56.60 vs. 252.48 ± 62.09; 238.65 ± 81.55 vs. 284.20 ± 66.66). The following anabolic/catabolic ratios fell after exercise: T/C (0.85 ± 0.54 vs. 0.54 ± 0.29), T/THE (0.66 ± 0.29 vs. 0.40 ± 0.08), T/THE+THF (0.38 ± 0.17 vs. 0.24 ± 0.06), DHEA/THE (0.22 ± 0.05 vs. 0.12 ± 0.05), DHEA/THF (0.34 ± 0.02 vs. 0.21 ± 0.01) and DHEA/THE+THF (0.12 ± 0.02 vs. 0.08 ± 0.03). The steroid profile showed that athletes were fatigued after finishing the competition and a catabolic state remained 24 hours later.

Bone metabolism markers and vitamin D in adolescent cyclists

This study aimed to describe bone metabolic activity in adolescent competitive cyclists compared to age-matched controls. The main result is that younger subjects present a higher bone turnover than the older ones. Moreover, cyclists under the age of 17 have higher scores on all markers than age-matched controls.

PURPOSE

The purpose of this study was to describe bone metabolic activity in adolescent competitive cyclists compared to age-matched controls.

METHODS

Twenty-two male adolescent cyclists between 14 and 20 years (y) and 20 age-matched controls participated in this study. Serum osteocalcin (OC), aminoterminal propeptide of type I procollagen (PINP), and β-isomerized C-telopeptides (β-CTX) were analyzed by electrochemiluminescence immunoassay (ECLIA); plasma 25 hydroxyvitamin D [25(OH)D] was analyzed by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Analysis of variance revealed no significant differences in bone metabolism markers and vitamin D between cyclists and controls. Cyclists over 17 y had a significantly lower concentration in bone formation and resorption biochemical markers compared to cyclists under 17 y (all P < 0.05). Moreover, controls over 17 y presented lower concentration for PINP (P < 0.05) compared to their peers under 17 y. Comparisons between cyclists and controls under 17 y revealed higher concentrations of OC and PINP (P < 0.05) in cyclists. Group interaction by age was found for OC, PINP, and β-CTX (P < 0.01). Cyclists over 17 y had higher concentrations of [25(OH)D] (P < 0.05) than age-matched controls.

CONCLUSIONS

The present results support the idea that cycling during adolescence may be associated to a decrease in bone turnover that may affect bone health later in life.

Novel bone metabolism-associated hormones: the importance of the pre-analytical phase for understanding their physiological roles

The endocrine function of bone is now a recognized feature of this tissue. Bone-derived hormones that modulate whole-body homeostasis, are being discovered as for the effects on bone of novel and classic hormones produced by other tissues become known. Often, however, the data regarding these last generation bone-derived or bone-targeting hormones do not give about a clear picture of their physiological roles or concentration ranges. A certain degree of uncertainty could stem from differences in the pre-analytical management of biological samples. The pre-analytical phase comprises a series of decisions and actions (i.e., choice of sample matrix, methods of collection, transportation, treatment and storage) preceding analysis. Errors arising in this phase will inevitably be carried over to the analytical phase where they can reduce the measurement accuracy, ultimately, leading discrepant results. While the pre-analytical phase is all important, in routine laboratory medicine, it is often not given due consideration in research and clinical trials. This is particularly true for novel molecules, such as the hormones regulating the endocrine function of bone. In this review we discuss the importance of the pre-analytical variables affecting the measurement of last generation bone-associated hormones and describe their, often debated and rarely clear physiological roles.

Whole-Body Cryotherapy in Athletes: From Therapy to Stimulation. An Updated Review of the Literature

Nowadays, whole-body cryotherapy is a medical physical treatment widely used in sports medicine. Recovery from injuries (e.g., trauma, overuse) and after-season recovery are the main purposes for application. However, the most recent studies confirmed the anti-inflammatory, anti-analgesic, and anti-oxidant effects of this therapy by highlighting the underlying physiological responses. In addition to its therapeutic effects, whole-body cryotherapy has been demonstrated to be a preventive strategy against the deleterious effects of exercise-induced inflammation and soreness. Novel findings have stressed the importance of fat mass on cooling effectiveness and of the starting fitness level on the final result. Exposure to the cryotherapy somehow mimics exercise, since it affects myokines expression in an exercise-like fashion, thus opening another possible window on the therapeutic strategies for metabolic diseases such as obesity and type 2 diabetes. From a biochemical point of view, whole-body cryotherapy not always induces appreciable modifications, but the final clinical output (in terms of pain, soreness, stress, and post-exercise recovery) is very often improved compared to either the starting condition or the untreated matched group. Also, the number and the frequency of sessions that should be applied in order to obtain the best therapeutic results have been deeply investigated in the last years. In this article, we reviewed the most recent literature, from 2010 until present, in order to give the most updated insight into this therapeutic strategy, whose rapidly increasing use is not always based on scientific assumptions and safety standards.

Bone turnover response is linked to both acute and established metabolic changes in ultra-marathon runners

Bone and energy metabolisms regulation depends on a two-way street aimed at regulating energy utilization. Mountain ultra-marathons are highly demanding aerobic performances that deeply affect the whole body homeostasis. In this study we aimed to investigate and characterize the metabolic profile (in terms of hormones involved in energy metabolism), the inflammatory adipokines, and the bone turnover; in particular the osteocalcin-mediated response has been compared in experienced mountain ultra-marathons runners versus control subjects. Serum concentrations of specific markers of bone turnover (pro-collagen type I N-terminal propeptide, carboxylated/undercarboxylated osteocalcin), measured by enzyme-linked immunosorbent assay, and metabolic hormones (C-peptide, insulin, glucagon, glucagon-like peptide, gastric-inhibitory peptide, ghrelin, leptin, resistin, and visfatin), measured by fluorescent-based multiplex assay, were compared before and after a 65 km mountain ultra-marathons in 17 trained runners and 12 age-matched controls characterized by a low physical activity profile. After the mountain ultra-marathons, runners experienced a reduction in pro-collagen type I N-terminal propeptide, though it remained higher than in controls; while carboxylated osteocalcin remained unchanged. Among the metabolic hormones, only glucagon and leptin were different between runners and controls at rest. C-peptide and leptin decreased after the mountain ultra-marathons in runners; while glucagon, glucagon-like peptide 1, resistin, and visfatin were all increased. Uncarboxylated osteocalcin (and uncarboxylated/carboxylated osteocalcin ratio) was decreased and this highly correlated with insulin and C-peptide levels. In conditions of high energy expenditure, homeostasis is maintained at expenses of bone metabolism. Changes in the uncarboxylated osteocalcin clearly mark the global energy needs of the body.

Associations among osteocalcin, leptin and metabolic health in children ages 9-13 years in the United States

Background

This study aimed to investigate the relationships among osteocalcin, leptin and metabolic health outcomes in children ages 9–13 years.

Methods

This was a cross-sectional analysis of baseline data from 161 boys and 157 girls (ages 9–13 years) who previously participated in a double-blinded randomized placebo controlled trial of vitamin D supplementation. Relationships among fasting serum total osteocalcin (tOC), undercarboxylated osteocalcin (ucOC), leptin, and metabolic health outcomes were analyzed.

Results

Approximately 52% of study participants were obese based on percent body fat cutoffs (>25% for boys and >32% for girls) and about 5% had fasting serum glucose within the prediabetic range (i.e. 100 to 125 mg/dL). Serum tOC was not correlated with leptin, glucose, insulin, HOMA-IR, or HOMA-β after adjusting for percent body fat. However, serum ucOC negatively correlated with leptin (partial r = −0.16; p = 0.04) and glucose (partial r = −0.16; p = 0.04) after adjustment for percent body fat. Leptin was a positive predictor of insulin, glucose, HOMA-IR, and HOMA-β after adjusting for age, sex and percent body fat (all p < 0.001).

Conclusions

These data depict an inverse relationship between leptin and various metabolic health outcomes in children. However, the notion that tOC or ucOC link fat with energy metabolism in healthy children was not supported.

Clinical trial registration number

NCT00931580.

Implications of exercise-induced adipo-myokines in bone metabolism

Physical inactivity has been recognized, by the World Health Organization as the fourth cause of death (5.5 % worldwide). On the contrary, physical activity (PA) has been associated with improved quality of life and decreased risk of several diseases (i.e., stroke, hypertension, myocardial infarction, obesity, malignancies). Bone turnover is profoundly affected from PA both directly (load degree is the key determinant for BMD) and indirectly through the activation of several endocrine axes. Several molecules, secreted by muscle (myokines) and adipose tissues (adipokines) in response to exercise, are involved in the fine regulation of bone metabolism in response to the energy availability. Furthermore, bone regulates energy metabolism by communicating its energetic needs thanks to osteocalcin which acts on pancreatic β-cells and adipocytes. The beneficial effects of exercise on bone metabolism depends on the intermittent exposure to myokines (i.e., irisin, IL-6, LIF, IGF-I) which, instead, act as inflammatory/pro-resorptive mediators when chronically elevated; on the other hand, the reduction in the circulating levels of adipokines (i.e., leptin, visfatin, adiponectin, resistin) sustains these effects as well as improves the whole-body metabolic status. The aim of this review is to highlight the newest findings about the exercise-dependent regulation of these molecules and their role in the fine regulation of bone metabolism.

The effect of cumulative endurance exercise on leptin and adiponectin and their role as markers to monitor training load

Leptin and adiponectin play an essential role in energy metabolism. Leptin has also been proposed as a marker for monitoring training load. So far, no studies have investigated the variability of these hormones in athletes and how they are regulated during cumulative exercise. This study monitored leptin and adiponectin in 15 endurance athletes twice daily in the days before, during and after a 9-day simulated cycling stage race. Adiponectin significantly increased during the race (p = 0.001) and recovery periods (p = 0.002) when compared to the baseline, while leptin decreased significantly during the race (p < 0.0001) and returned to baseline levels during the recovery period. Intra-individual variability was substantially lower than inter-individual variability for both hormones (leptin 34.1 vs. 53.5%, adiponectin 19% vs. 37.2%). With regards to exercise, this study demonstrated that with sufficient, sustained energy expenditure, leptin concentrations can decrease within the first 24 hours. Under the investigated conditions there also appears to be an optimal leptin concentration which ensures stable energy homeostasis, as there was no significant decrease over the subsequent race days. In healthy endurance athletes the recovery of leptin takes 48-72 hours and may even show a supercompensation-like effect. For adiponectin, significant increases were observed within 5 days of commencing racing, with these elevated values failing to return to baseline levels after 3 days of recovery. Additionally, when using leptin and adiponectin to monitor training loads, establishing individual threshold values improves their sensitivity.

Osteocartilaginous metabolic markers change over a 3-week stage race in pro-cyclists

Evidence suggests that endurance and even recreational cycling may stimulate bone resorption; however, little is known about cartilage response to endurance cycling exercise. We investigated effort-dependent changes in bone turnover and cartilage biomarkers in blood and urine samples from elite cyclists during a 3-week stage race. Whole blood and urine samples were collected the day before the start of the race, at mid and end-race for serum and urinary CTx-I, NTx-I, PINP, COMP (only in serum), and CTx-II analysis by enzyme-linked immunosorbent assay. The values were corrected for plasma volume or creatinine excretion, respectively, and correlated with power output (corrected for body weight) and net energy expenditure. Bone marker concentrations in both serum and urine were slightly but significantly decreased. Among the cartilage degradation markers, only CTx-II was decreased, while COMP remained unchanged. The changes in bone and cartilage turnover indexes were correlated with the indexes of physical effort and energy consumption. Strenuous physical effort, in the absence of mechanical loading, slows bone metabolism and only minimally affects cartilage turnover. Since changes in plasma and urine volume, which normally occur in exercising athletes, can mask these effects, biomarker concentrations need to be corrected for shifts in plasma volume and urinary creatinine for correct interpretation of the data.

The effects of a calcium-rich pre-exercise meal on biomarkers of calcium homeostasis in competitive female cyclists: a randomised crossover trial

Cycling is recognised as a sport in which there is a high incidence of poor bone health. Sweat calcium losses may contribute to this.

A four-season molecule: osteocalcin. Updates in its physiological roles

Osteocalcin (OC) is the main non-collagenous hydroxyapatite-binding protein synthesized by osteoblasts, odontoblasts, and hypertrophic chondrocytes. It has a regulatory role in mineralization and it is considered a marker of bone cell metabolism. Recent findings evidenced new extra-skeletal roles for OC, depicting it as a real hormone. OC shares many functional features with the common hormones, such as tissue-specific expression, circadian rhythm, and synthesis as a pre-pro-molecule. However, it has some peculiar features making it a unique molecule: OC exists in different forms based on the degree of carboxylation. Indeed, OC has three glutamic acid residues, in position 17, 21, and 24, which are subject to γ-carboxylation, through the action of a vitamin K-dependent γ-glutamyl carboxytransferase. The degree of carboxylation, and thus the negative charge density, determines the affinity for the calcium ions deposited in the extracellular matrix of the bone. The modulation of the carboxylation could, thus, represent the mechanism by which the body controls the circulating levels, and hence the hormonal function, of OC. There are evidences linking OC, and the bone metabolism, with a series of endocrine (glucose metabolism, energy metabolism, fertility) physiological (muscle activity) and pathological functions (ectopic calcification). Aim of this review is to give a full overview of the physiological roles of OC by collecting the newest experimental findings on this intriguing molecule.

Reciprocal regulation of calcium-/phosphate-regulating hormones in cyclists during the Giro d'Italia 3-week stage race

Calcium and phosphate are essential for cell functions, and their serum concentrations result from the balance between intestinal absorption, bony storage, and urinary excretion. Fibroblast growth factor 23 (FGF23), expressed by osteocytes and osteoblasts, acts in the kidney, leading to hypophosphatemia and low 1,25-dihydroxycholecalciferol synthesis, but suppresses parathyroid function. The aim of this study was to explore the effects of a high-energy demanding cycling race on this bone-kidney-parathyroid axis. We studied nine cyclists during the 2011 Giro d'Italia stage race. Pre-analytical and analytical phases followed academic and anti-doping recommendations. Serum parathyroid hormone (PTH), 25(OH)D, total calcium, inorganic phosphorus, and plasma FGF23 were measured on days -1, 12, and 22 and corrected for changes in plasma volume. Dietary calcium and phosphorus, anthropometric parameters (height, weight, and body mass index) and indexes of metabolic effort (net energy expenditure, power output) were recorded. Dietary calcium and phosphorus intakes were kept at the same levels throughout the race. Twenty-five (OH)D, PTH, and calcium concentrations remained stable. FGF23 increased 50% with a positive correlation with the indexes of metabolic effort and, consequently, phosphorous decreased, although only in the first half. The strong metabolic effort acts on the bone-kidney-parathyroid system, and the rise in FGF23 plasma concentration might be aimed at maintaining calcium and phosphorus homeostasis.