Acute response of plasma markers of bone turnover to a single bout of resistance training or plyometrics

A single bout of jumping exercise does not modulate serum markers of bone formation or bone resorption throughout a 24 h period

INTRODUCTION

This randomized, cross-over trial assessed the effect of a single bout of high-impact exercise on serum markers of bone formation and bone resorption over a 24 h period.

METHODS

Twenty healthy males and females performed a single bout of brief jumping exercise (EXC) or no exercise (CON), 55 min following consumption of a standard breakfast. Blood markers of bone formation (P1NP) and bone resorption (CTX-I) were assessed before (t = 0 h) and over a 5 h period after breakfast, and following 24 h of post-exercise recovery (t = 24 h).

RESULTS

Serum CTX-I concentrations decreased during the 5 h postprandial period (time-effect, P < 0.001) with no differences between conditions (time x condition, P = 0.14). After a ~ 16 % decline during the first 30 min following breakfast, serum P1NP concentrations gradually returned to baseline values during the 5 h postprandial period, with no differences in the overall response between conditions (time-effect, P < 0.001; time x condition, P = 0.25). Fasted serum CTX-I concentrations decreased from 0.33 ± 0.15 and 0.35 ± 0.15 ng/mL at baseline, to 0.31 ± 0.13 and 0.31 ± 0.16 ng/mL at t = 24 h in CON and EXC, respectively, with no differences between conditions (time-effect, P < 0.01; time x condition, P = 0.70). Fasted serum P1NP concentrations did not change from baseline to t = 24 h in both CON (baseline: 76 ± 27 ng/mL, t = 24 h: 79 ± 26 ng/mL) and EXC (baseline: 80 ± 24 ng/mL, t = 24 h: 77 ± 29 ng/mL; time-effect, P = 0.89), with no differences between conditions (time x condition, P = 0.22).

CONCLUSION

High-impact exercise does not modulate the concentrations of the serum marker of bone formation P1NP and the serum marker of bone resorption CTX-I throughout a 24 h recovery period in healthy adults.

Time of day of exercise does not affect the beneficial effect of exercise on bone structure in older female rats

Background: Circadian clock genes are expressed in bone and biomarkers of bone resorption and formation exhibit diurnal patterns in animals and humans. Disruption of the diurnal rhythms may affect the balance of bone turnover and compromise the beneficial effects of exercise on bone. Objective: This study investigated whether the time of day of exercise alters bone metabolism in a rodent model. We hypothesized that exercise during the active phase results in greater bone mass than exercise during the rest phase in older female rats. Methods: Fifty-five, female 12-month-old Sprague Dawley rats were randomly assigned to four treatment groups (n = 13-14/group). Rats were subjected to no exercise or 2 h of involuntary exercise at 9 m/min and 5 days/wk for 15 weeks using motor-driven running wheels at Zeitgeber time (ZT) 4-6 (rest phase), 12-14 (early active phase), or 22-24 (late active phase). ZT 0 is defined as light on, the start of the rest phase. A red lamp was used at minimal intensity during the active, dark phase exercise period, i.e., ZT 12-14 and 22-24. Bone structure, body composition, and bone-related cytokines in serum and gene expression in bone were measured. Data were analyzed using one-way ANOVA followed by Tukey-Kramer post hoc contrasts. Results: Exercise at different ZT did not affect body weight, fat mass, lean mass, the serum bone biomarkers, bone structural or mechanical parameters, or expression of circadian genes. Exercise pooled exercise data from different ZT were compared to the No-Exercise data (a priori contrast) increased serum IGF-1 and irisin concentrations, compared to No-Exercise. Exercise increased tibial bone volume/total volume (p = 0.01), connectivity density (p = 0.04), and decreased structural model index (p = 0.02). Exercise did not affect expression of circadian genes. Conclusion: These data indicate that exercise is beneficial to bone structure and that the time of day of exercise does not alter the beneficial effect of exercise on bone in older female rats.

High-impact jumping mitigates the short-term effects of low energy availability on bone resorption but not formation in regularly menstruating females: A randomized control trial

Low energy availability (LEA) is prevalent in active individuals and negatively impacts bone turnover in young females. High-impact exercise can promote bone health in an energy efficient manner and may benefit bone during periods of LEA. Nineteen regularly menstruating females (aged 18-31 years) participated in two three-day conditions providing 15 (LEA) and 45 kcals kg fat-free mass-1  day-1 (BAL) of energy availability, each beginning 3 ± 1 days following the self-reported onset of menses. Participants either did (LEA+J, n = 10) or did not (LEA, n = 9) perform 20 high-impact jumps twice per day during LEA, with P1NP, β-CTx (circulating biomarkers of bone formation and resorption, respectively) and other markers of LEA measured pre and post in a resting and fasted state. Data are presented as estimated marginal mean ± 95% CI. P1NP was significantly reduced in LEA (71.8 ± 6.1-60.4 ± 6.2 ng mL-1 , p < 0.001, d = 2.36) and LEA+J (93.9 ± 13.4-85.2 ± 12.3 ng mL-1 , p < 0.001, d = 1.66), and these effects were not significantly different (time by condition interaction: p = 0.269). β-CTx was significantly increased in LEA (0.39 ± 0.09-0.46 ± 0.10 ng mL-1 , p = 0.002, d = 1.11) but not in LEA+J (0.65 ± 0.08-0.65 ± 0.08 ng mL-1 , p > 0.999, d = 0.19), and these effects were significantly different (time by condition interaction: p = 0.007). Morning basal bone formation rate is reduced following 3 days LEA, induced via dietary restriction, with or without high-impact jumping in regularly menstruating young females. However, high-impact jumping can prevent an increase in morning basal bone resorption rate and may benefit long-term bone health in individuals repeatedly exposed to such bouts.

Effects of running a marathon on sclerostin and parathyroid hormone concentration in males aged over 50

The aim of our study was to verify whether running a marathon (32nd Wroclaw Marathon) was associated with changes in sclerostin and intact PTH (iPTH) concentration in middle-aged males. We enrolled 33 males who completed the marathon race. Blood samples were taken 60 minutes before (V1), immediately after (V2), and 7 days after the run (V3). The mean serum sclerostin concentration was 42.4 ± 10.8 pmol/L at V1, increased to 62.9 ± 12.6 pmol/L at V2 (t= -11.206; p < 0.001) and returned to baseline in V3 (t = 8.344; p < 0.001, V3 vs. V2). A similar trend was recorded for iPTH (t= -7.440; p < 0.001, for V2 vs. V1; t = 6.229; p < 0.001, for V3 vs. V2), at V3, iPTH levels remained significantly higher than V1 (t= -2.759; p = 0.010). The results of our study suggest that, in middle-aged males, running a marathon affects skeletal metabolism by activating two counteracting mechanisms, although temporarily overlapping: first, by a sudden inhibition of bone formation, through induction sclerostin expression and, secondly, by a long-lasting induction of PTH, which also guarantees the maintenance of adequate circulating levels of calcium. The net effect would be the maintenance of adequately high levels of circulating calcium to be used for neuromuscular activity and muscle contraction.

Exerkines and long-term synaptic potentiation: Mechanisms of exercise-induced neuroplasticity

Physical exercise may improve cognitive function by modulating molecular and cellular mechanisms within the brain. We propose that the facilitation of long-term synaptic potentiation (LTP)-related pathways, by products induced by physical exercise (i.e., exerkines), is a crucial aspect of the exercise-effect on the brain. This review summarizes synaptic pathways that are activated by exerkines and may potentiate LTP. For a total of 16 exerkines, we indicated how blood and brain exerkine levels are altered depending on the type of physical exercise (i.e., cardiovascular or resistance exercise) and how they respond to a single bout (i.e., acute exercise) or multiple bouts of physical exercise (i.e., chronic exercise). This information may be used for designing individualized physical exercise programs. Finally, this review may serve to direct future research towards fundamental gaps in our current knowledge regarding the biophysical interactions between muscle activity and the brain at both cellular and system levels.

Acute effects of the resistance exercise associated with different blood flow restriction pressures on bone remodeling biomarkers

Background

The present study analyzed the acute responses of parathyroid hormone (PTH) and bone-specific alkaline phosphatase (BSAP) to the low-intensity resistance exercise with blood flow restriction using different occlusion pressures.

Methods

Twelve women completed the three protocols of this crossover study: resistance exercise without blood flow restriction (RE), resistance exercise with blood flow restriction and occlusion pressure corresponding to 70% of systolic blood pressure (RE + BFR70), and resistance exercise with blood flow restriction and occlusion pressure corresponding 130% of systolic blood pressure (RE + BFR130). All exercises were performed in a guided squat apparatus with load corresponded to 30% of one-repetition maximum test.

Results

Relative to resting levels, PTH concentrations decreased significantly (p = .000) post-exercise in all groups and increased significantly (p = .000) 15 min post-exercise in RE + BFR70 and RE + BFR130 groups; PTH concentrations returned to resting levels after the 30-min recovery period in all groups. There was no significant difference (p >.05) between BSAP values at rest and 30 min post-exercise.

Conclusion

In conclusion, our results showed that protocols with blood flow restriction using occlusion pressures equivalent to 70% and 130% of systolic blood pressure were more effective than RE alone to induce PTH peaks, and to promote a metabolic condition favorable to bone anabolism.

Acute Effects of Strength and Endurance Training on Bone Turnover Markers in Young Adults and Elderly Men

CONTEXT

Exercise is recognized as an important strategy to prevent bone loss, but its acute effects on bone turnover markers (BTMs) and related markers remain uncertain.

OBJECTIVE

To assess the acute effects of two different exercise modes on BTMs and related markers in young adults of both sexes and elderly men.

DESIGN SETTING PARTICIPANTS

This was a three-group crossover within-subjects design study with a total of 53 participants-19 young women (aged 22-30), 20 young men (aged 21-30 years), and 14 elderly men (aged 63-74 years)-performing two different exercise sessions [strength training (ST) and high-intensity interval training (HIIT)] separated by 2 weeks, in a supervised laboratory setting.

MAIN OUTCOME MEASURES

Plasma volume-corrected serum measurements of the BTMs C-terminal telopeptide of type 1 collagen (CTX-I) and procollagen of type 1 N-terminal propeptide (P1NP), total osteocalcin (OC), sclerostin, and lipocalin-2 (LCN2) at baseline, immediately after, and 3 and 24 h after each of the two exercise modes were performed.

RESULTS AND CONCLUSION

Analyses revealed sex- and age-dependent differences in BTMs and related bone markers at baseline and time-, sex-, and age-dependent differences in response to exercise. No differences between exercise modes were observed for BTM response except for sclerostin in young men and LCN2 in elderly men. An acute, transient, and uniform increase in P1NP/CTX-1 ratio was found in young participants, demonstrating that beneficial skeletal effects on bone metabolism can be attained through both aerobic endurance and resistance exercise, although this effect seems to be attenuated with age. The acute effects of exercise on bone-related biomarkers were generally blunted after 24 h, suggesting that persistent alterations following prolonged exercise interventions should be assessed at later time points.

Changes in blood bone markers after the first and second bouts of whole-body eccentric exercises

The present study compared the first (EC1) and second (EC2) bouts of whole-body eccentric exercises to examine the effects of the magnitude of muscle damage on changes in blood bone markers. Fifteen sedentary young men performed nine eccentric exercises of arm, leg and trunk muscles, and repeated them two weeks later. Blood samples were taken before and two hours and one to five days following each bout to analyze plasma creatine kinase (CK) activity and myoglobin concentration, serum tartrate resistant acid phosphatase (TRAP), type 1 C-terminal telopeptide (CTX-1), procollagen type I N-terminal propeptide (P1NP), bone-specific alkaline phosphatase (BAP), undercarboxylated-osteocalcin (ucOCN), carboxylated-osteocalcin (cOCN), and leptin concentrations. All except ucOCN changed significantly (P<0.05) after both bouts. When comparing bouts for peak changes, P1NP (bone formation marker) and CTX-1 (bone resorption marker) increased less after EC2 (peak: 137±96% and 7±6%, respectively) than after EC1 (146±80% and 30±21%, respectively), whereas BAP (bone formation marker) increased more after EC2 (18±16%) than after EC1 (4±15%) (P<0.05). Leptin (49±58%) and cOCN (14±10%) increased more (P<0.05) after EC2 than after EC1 (-30±15%, 9±26%). Significant (P<0.05) correlations were evident between peak CK activity and peak CTX-1 (r=0.847), P1NP (r=0.815), BAP (r=-0.707), ucOCN (r=0.627), cCON (r=-0.759) and leptin (r=-0.740) changes after EC1, but many of these correlations disappeared after EC2. This was also found for the relationships between other muscle damage markers (myoglobin, muscle soreness and muscle strength) and the bone markers. It was concluded that bone turnover was affected by eccentric exercise, but muscle damage was unfavorable for bone formation.

Ibuprofen taken before exercise blunts the IL-6 response in older adults but does not alter bone alkaline phosphatase or c-telopeptide

INTRODUCTION

Non-steroidal anti-inflammatory drugs (NSAIDs) taken before exercise have been shown to impair bone formation. NSAIDs also suppress inflammatory cytokines, such as interleukin-6 (IL-6), that can have pro-resorptive effects. It is unclear how taking NSAIDs timed around exercise influences inflammatory and bone biomarkers following an acute exercise bout in older adults.

PURPOSE

To determine if timing of ibuprofen use relative to a single exercise bout has acute effects on serum IL-6, bone-specific alkaline phosphatase (BAP, marker of bone formation), and c-telopeptide of type I collagen (CTX, marker of bone resorption).

METHODS

As part of a 36-week exercise intervention, participants aged 60 to 75 years were randomized to 3 groups: placebo before and after exercise (PP), ibuprofen before and placebo after exercise (IP), or placebo before and ibuprofen after exercise (PI). Acute responses were studied in a subset of participants (12 PP, 17 IP, 13 PI). Blood was sampled before and immediately, 30 min, and 60 min after exercise for IL-6, BAP, and CTX.

RESULTS

The exercise-induced increase in IL-6 was blunted in response to IP when compared to PI 60-min after exercise (p < 0.001). There were no significant differences in the change in BAP or CTX between groups at any time points CONCLUSION: Ibuprofen taken before exercise dampened the inflammatory response to exercise but had no effects on bone biomarkers in older adults. It may be necessary to monitor changes for a longer time interval after an acute exercise bout to determine whether bone turnover is altered by ibuprofen or other NSAIDs.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT00462722; Posted 04/19/2007.

Insulin-like growth factor-1 positively associated with bone formation markers and creatine kinase in adults with general physical activity

BACKGROUND

The Insulin-like growth factor-1 (IGF-1) is primarily synthesized by hepatocytes in a growth hormone (GH)-dependent manner, it is also produced by bone and muscle. The effects of exercise on the associations between IGF-1 levels and bone turnover markers (BTM) were found in the previous studies. However, the associations between the levels of IGF-1 and BTM, liver function tests, and skeletal muscle markers in adults with general physical activity were not clear.

METHODS

Ninety-four participants were recruited from healthy survey. Blood samples were collected to analyze the levels of IGF-1, total protein (TP), albumin (Alb), total bilirubin (T-Bil), direct bilirubin (D-Bil), aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), bone alkaline phosphatase (BALP), lactate dehydrogenase (LDH), creatine kinase (CK), creatinine (CRTN), and glucose. Urine samples were collected to analyze the CRTN and deoxypyridinoline (Dpd) levels.

RESULTS

The positively significant associations were found between the IGF-1 levels and the levels of ALP, BALP, and CK, respectively. No significant associations were found between the IGF-1 levels and the levels of TP, Alb, A/G, T-Bil, D-Bil, AST, ALT, LDH, glucose, urinary CRTN, urinary Dpd, and Dpd/CRTN ratios, respectively.

CONCLUSION

The serum IGF-1 levels associated with the levels of skeletal muscle and bone formation markers (BFM), not the bone resorption markers under general physical activity in the healthy adults. The physician needs to consider the effects of bone formation and skeletal muscle markers on the IGF-1 levels in the management of IGF-1-related disorders.

Osteokines and Bone Markers at Rest and following Plyometric Exercise in Pre- and Postmenopausal Women

The effect of plyometric exercise on bone biomarkers has been studied in pediatric and young adult populations in order to better understand how exercise influences bone homeostasis. However, there are no such data in postmenopausal women, a group characterized by an uncoupling of the bone resorption-formation cycle. This study examined the serum concentrations of sclerostin, dickkopf-1 (DKK1), c-terminal crosslinking telopeptides of type I collagen (CTXI), and procollagen type I amino-terminal propeptide (PINP) at rest and following a single bout of plyometric exercise in 20 premenopausal (23.1 ± 2.3 years) and 20 postmenopausal women (57.9 ± 4.3 years). The exercise consisted of 128 jumps, organized into 5 circuit stations. Blood samples were obtained prior to and 5 min, 1 h, and 24 h postexercise. At rest, postmenopausal women had significantly higher sclerostin and CTXI, but lower DKK1 than premenopausal women. Sclerostin increased 5 min postexercise only in the premenopausal group. DKK1 decreased 24 h postexercise in the premenopausal women while it decreased 1 h postexercise in the postmenopausal women. In both groups, CTXI did not change across time and PINP decreased 5 min and 1 h postexercise (p < 0.05). The PINP/CTXI ratio decreased 5 min and 1 h postexercise then significantly increased 24 h postexercise only in premenopausal women. These results indicate that although plyometric exercise is effective in eliciting osteoanabolic effects in younger women; such an effect is not evident in postmenopausal women.

Short-Term Intermittent Hypoxic Resistance Training Does Not Impair Osteogenic Response in Sea Level Residents

Background: Osteogenic responses induced by training under hypoxia remain unclear. We aimed to investigate whether intermittent hypoxic resistance training affects osteogenic responses. Materials and Methods: Sixteen male participants underwent resistance training under normoxia (NRT; n = 7) or hypoxia (HRT; O₂ = 14.4%, n = 9), twice a week for 8 weeks. The HRT group exercised and rested for 30 minutes under hypoxia, with total hypoxic exposure time in one session of ∼60 minutes. At pre- and postexperiment, bone mineral density (BMD) of the whole body and right proximal femur was measured. At the first and last training sessions, bone alkaline phosphatase (BAP), osteocalcin (OC), cross-linked N-telopeptide of type I collagen (NTx), type I collagen cross-linked C-telopeptide (ICTP), interleukin-6 (IL-6), and blood lactate (La) concentration were analyzed at rest and postexercise. Results: BMD did not change with training and hypoxia. Although BAP, OC, and ICTP levels at rest significantly increased with training (p < 0.01, 0.05, and 0.05, respectively), they did not change with hypoxia. NTx and IL-6 did not change. Additionally, changing patterns of bone markers and La induced by a single bout of exercise were similar among groups in both training sessions. Conclusions: Short-term resistance training enhanced overall bone metabolism, regardless of the oxygen level. Hypoxia has no effects on osteogenic responses.

Acute response of biochemical bone turnover markers and the associated ground reaction forces to high-impact exercise in postmenopausal women

The aim of the study was to examine the acute response of biochemical bone turnover markers (BTM) to high-impact jumping exercise, and to quantify the ground reaction forces (GRF) achieved during each jumping exercise, in postmenopausal women. In a randomized controlled cross-over study over three days, 29 postmenopausal women (age (mean±SD): 60.0±5.6 years) were randomly assigned to 6 x 10 repetitions of three different jumps: countermovement jump (CMJ), drop jump (DJ), diagonal drop jump (DDJ). A fourth day without jumping served as a control (CON). Blood samples were collected before (PRE), after (POST), and 2 hours after (2Hr) exercise. Bone turnover was evaluated by bone formation markers (procollagen type-1 amino-terminal propeptide (P1NP) and osteocalcin (OC)) and the bone resorption marker C-terminal telopeptide of type-1 collagen (CTX). Peak anteroposterior (Fx), mediolateral (Fy), and vertical (Fz) GRF were measured using a force platform. From PRE to POST, P1NP increased (p<0.01) by 7.7±1.8%, 9.4±1.3%, and 10.6±1.6% for CMJ, DJ, and DDJ, which were higher (p<0.01) than CON. OC increased (p<0.05) by 5.5±1.8% for DJ, which was higher (p<0.05) than CON. CTX was not significantly changed at POST. There were no significant differences in BTM Δ-values between the jumps at any time point. For the CMJ, the combined three-axis peak GRF was positively associated with the PRE to POST Δ-change in P1NP (r=0.71, p<0.05). The acute, jumping-induced increase in P1NP and OC without any rise in CTX may indicate increased bone formation. Moreover, the study shows a dose-response relationship between GRF and the acute P1NP response after countermovement jumps.

The time course and mechanisms of change in biomarkers of joint metabolism in response to acute exercise and chronic training in physiologic and pathological conditions

PURPOSE

The benefits of exercise across the lifespan and for a wide spectrum of health and diseases are well known. However, there remains less clarity as to the effects of both acute and chronic exercise on joint health. Serum biomarkers of joint metabolism are sensitive to change and have the potential to differentiate between normal and adverse adaptations to acute and chronic load. Therefore, the primary objective of this review is to evaluate how serum biomarkers can inform our understanding of how exercise affects joint metabolism.

METHODS

A comprehensive literature search was completed to identify joint biomarkers previously used to investigate acute and chronic exercise training.

RESULTS

Identified biomarkers included those related to joint cartilage, bone, synovium, synovial fluid, and inflammation. However, current research has largely focused on the response of serum cartilage oligomeric matrix protein (COMP) to acute loading in healthy young individuals. Studies demonstrate how acute loading transiently increases serum COMP (i.e., cartilage metabolism), which is mostly dependent on the duration of exercise. This response does not appear to be associated with any lasting deleterious changes, cartilage degradation, or osteoarthritis.

CONCLUSION

Several promising biomarkers for assessing joint metabolism exist and may in future enhance our understanding of the physiological response to acute and chronic exercise. Defining 'normal' and 'abnormal' biomarker responses to exercise and methodological standardisation would greatly improve the potential of research in this area to understand mechanisms and inform practice.

The effect of intermittent running on biomarkers of bone turnover

Intermittent exercise might be an efficient means of exercise for improving bone strength and quality. The aim of our study was to examine the effect of intermittent running on bone turnover markers using altered exercise-to-rest intervals. Twelve males completed one control (no exercise), and three, 45-min intermittent protocols (5, 20, and 80 s intervals) matched for distance and speed. Fasted venous blood samples were collected at baseline, 1, 2 and 24 h post-exercise. Carboxyterminal crosslinked telopeptide (CTX-I) and procollagen type 1 amino-terminal propeptide (P1NP) were used as markers of bone resorption and formation. After adjustment for baseline, CTX-I concentration at 1 h was higher (very likely to most likely small) for 5 s (30.2%; ±90% confidence limits: 10%), 20 s (2.9.0%; ±10%) and 80 s (32.0%; ±10%) compared to control. The very likely small effect remained for 5 s at 2 h (30.2%; ±15%). The effect for 20 and 80 s was possibly trivial and possibly small/possibly trivial (∼14.5%; ±∼15%). Differences in P1NP concentrations were likely to very likely trivial (∼7.4%; ±∼7.6%). Circulating CTX-I concentration is affected acutely by intermittent running with short-interval (5 s) intermittent loading resulting in a prolonged attenuation in circadian rhythm of CTX-I up to 2 h that was not demonstrated as clearly by longer intervals despite matched internal and external training load.

Effects of High-Intensity Interval Running Versus Cycling on Sclerostin, and Markers of Bone Turnover and Oxidative Stress in Young Men

This study compared sclerostin's response to impact versus no-impact high-intensity interval exercise in young men and examined the association between exercise-induced changes in sclerostin and markers of bone turnover and oxidative stress. Twenty healthy men (22.3 ± 2.3 years) performed two high-intensity interval exercise trials (crossover design); running on treadmill and cycling on cycle ergometer. Trials consisted of eight 1 min running or cycling intervals at ≥ 90% of maximal heart rate, separated by 1 min passive recovery intervals. Blood samples were collected at rest (pre-exercise), and 5 min, 1 h, 24 h, and 48 h following each trial. Serum levels of sclerostin, cross-linked telopeptide of type I collagen (CTXI), procollagen type I amino-terminal propeptide (PINP), thiobarbituric acid reactive substances (TBARS), and protein carbonyls (PC) were measured. There was no significant time or exercise mode effect for PINP and PC. A significant time effect was found for sclerostin, CTXI, and TBARS with no significant exercise mode effect and no significant time-by-mode interaction. Sclerostin increased from pre- to 5 min post-exercise (47%, p < 0.05) and returned to baseline within 1 h following the exercise. CTXI increased from pre- to 5 min post-exercise (28%, p < 0.05), then gradually returned to baseline by 48 h. TBARS did not increase significantly from pre- to 5 min post-exercise but significantly decreased from 5 min to 48 h post-exercise. There were no significant correlations between exercise-induced changes in sclerostin and any other marker. In young men, sclerostin's response to high-intensity interval exercise is independent of impact and is not related to changes in bone turnover and oxidative stress markers.

Sclerostin and parathyroid hormone responses to acute whole-body vibration and resistance exercise in young women

Whole-body vibration (WBV) has been shown to improve bone mineral density, and muscle strength and power. No studies to date have examined sclerostin and parathyroid hormone (PTH) responses to WBV combined with resistance exercise (RE). This randomized crossover study compared acute serum sclerostin and PTH responses to RE and WBV + RE in young women (n = 9) taking oral contraceptives. Participants were exposed to 5 1-min bouts of vibration (20 Hz, 3.38 peak-peak displacement, separated by 1 min of rest) before high intensity resistance exercise. Fasting blood samples were obtained before (PRE), immediately after WBV (POSTWBV), immediately post RE (IP) and 30 min post RE (30P). Pre-exercise sclerostin and PTH levels were not significantly different between conditions. Sclerostin levels significantly (p < 0.05) increased from PRE to IP for the WBV + RE condition, then decreased back to the pre-exercise level. PTH significantly decreased from PRE to 30P (p < 0.05) and IP to 30P (p < 0.01) for both conditions. Correcting for hemoconcentration eliminated the significant sclerostin responses, but the significant decrease in PTH remained (p < 0.05). There were no significant relationships found between sclerostin and PTH. In conclusion, sclerostin concentrations increased in response to the WBV + RE condition, which may have been mediated by plasma volume shifts. There was no transient PTH increase, but it showed a large decrease at 30P for both conditions. Based on these findings, the addition of WBV exposures prior to high intensity RE did not alter sclerostin and PTH responses to RE in young women.

Response of Sclerostin and Bone Turnover Markers to High Intensity Interval Exercise in Young Women: Does Impact Matter?

This study examined potential exercise-induced changes in sclerostin and in bone turnover markers in young women following two modes of high intensity interval exercise that involve impact (running) or no-impact (cycling). Healthy, recreationally active, females (n=20; 22.5±2.7 years) performed two exercise trials in random order: high intensity interval running (HIIR) on a treadmill and high intensity interval cycling (HIIC) on a cycle ergometer. Trials consisted of eight 1 min running or cycling intervals at ≥90% of maximal heart rate, separated by 1 min passive recovery intervals. Blood samples were collected at rest (pre-exercise) and 5 min, 1h, 24h, and 48h following each exercise trial. Serum was analyzed for sclerostin, cross linked telopeptide of type I collagen (CTXI), and procollagen type I amino-terminal propeptide (PINP). A significant time effect was found for sclerostin, which increased from pre-exercise to 5 min after exercise in both trials (100.2 to 131.6 pg/ml in HIIR; 102.3 to 135.8 pg/ml in HIIC, p<0.001) and returned to baseline levels by 1h, with no difference between exercise modes and no exercise mode-by-time interaction. CTXI did not significantly change following either trial. PINP showed an overall time effect following HIIR, but none of the post hoc pairwise comparisons were statistically significant. In young women, a single bout of high intensity exercise induces an increase in serum sclerostin, irrespective of exercise mode (impact versus no-impact), but this response is not accompanied by a response in either bone formation or resorption markers.

Physical activity may be a potent regulator of bone turnover biomarkers in healthy girls during preadolescence

This study investigated the effects of different levels of habitual physical activity (PA) assessed by pedometry on bone turnover markers of preadolescent girls according to a cross-sectional experimental design. Sixty prepubertal girls of similar chronological age, bone age, maturity level, and nutritional status were assigned to a low PA (LPA; n = 25), a moderate PA (MPA; n = 17), or a high PA (HPA; n = 18) group. Dual-energy X-ray absorptiometry was used to measure areal bone mineral density (BMD) and bone mineral content (BMC) of the lumbar spine (L2-L4) and dominant hip (femoral neck and trochanter). Blood was collected for the measurement of alkaline phosphatase (ALP), bone-specific ALP (BSAP), procollagen type I N-terminal propeptide (PINP), C-terminal telopeptide of collagen I (CTX), parathyroid hormone (PTH), osteocalcin, thyroid-stimulating hormone, estradiol, testosterone, luteinizing hormone, and follicle-stimulating hormone concentrations. ANOVA revealed that the HPA group (18,695 ± 1244 steps per day) had a lower daily energy intake and body mass than the MPA group (10,774 ± 521 steps per day) and the LPA group (7633 ± 1099 steps per day). The HPA group had higher (P < 0.05) lumbar and hip BMD and hip BMC than the LPA group and higher (P < 0.05) lumbar BMD than the MPA group. The MPA group had higher (P < 0.05) hip BMC than the LPA group. The HPA group had greater (P < 0.05) values of BSAP, PINP, and ALP and lower (P < 0.05) values of PTH and CTX than the LPA group but not the MPA group. A partial correlation analysis (adjusted for body mass index) revealed a positive correlation of steps per day with BMD and BSAP concentration and a negative correlation with PTH and CTX concentration. In conclusion, PA increases BMD and BMC of premenarcheal girls by favoring bone formation over bone resorption.

Serum sclerostin decreases following 12months of resistance- or jump-training in men with low bone mass

PURPOSE

We previously reported that 12months of resistance training (RT, 2×/wk, N=19) or jump training (JUMP, 3×/wk, N=19) increased whole body and lumbar spine BMD and increased serum bone formation markers relative to resorption in physically active (≥4h/wk) men (mean age: 44±2y; median: 44y) with osteopenia of the hip or spine. The purpose of this secondary analysis was to examine the effects of the RT or JUMP intervention on potential endocrine mediators of the exercise effects on bone, specifically IGF-I, PTH and sclerostin.

METHODS

Fasting blood samples were collected after a 24-h period of no exercise at baseline and after 12months of RT or JUMP. IGF-I, PTH and sclerostin were measured in serum by ELISA. The effects of RT or JUMP on IGF-I, PTH and sclerostin were evaluated using 2×2 repeated measures ANOVA (time, group). This study was conducted in accordance with the Declaration of Helsinki and was approved by the University of Missouri IRB.

RESULTS

Sclerostin concentrations in serum significantly decreased and IGF-I significantly increased after 12months of RT or JUMP; while PTH remained unchanged.

CONCLUSION

The beneficial effects of long-term, progressive-intensity RT or JUMP on BMD in moderately active men with low bone mass are associated with decreased sclerostin and increased IGF-I.

Impact of physical activity and mechanical loading on biomarkers typically used in osteoarthritis assessment: current concepts and knowledge gaps

There is an ongoing need to develop prognostic and diagnostic biomarkers for osteoarthritis (OA). Understanding how biomarkers change in response to physical activity may be vital for understanding if a patient has a joint that is failing to adapt to a given loading stimulus. The purpose of this review is to describe how biomarker changes after joint loading may help detect early OA and determine prognosis. This may help to inform and more specifically target interventions and clinical trials. We conducted a critical review of the relevant literature that was published to January 2016. There is extensive OA biomarker research, specifically basal biomarker concentrations; however, there is limited research surrounding biomarker response to load. Some of this limited research includes the response of minimal biomarkers reflecting bone, synovium, inflammatory, and cartilage responses to load. Biomarker changes occur in bone and cartilage in response to a variety of activities and are influenced by variables such as body weight, load, vibration, and activity time. Biomarker responses to loading tasks may serve as a measure of overall joint health and be predictive of structural changes. Biomarkers adapt to training over time, and this may indicate a need for a gradual return to physical activity after an injury to allow time for joint tissues to adapt to load. Biomarker responses to physical activity may be monitored to determine appropriate loading levels and safety for return to activity.

The repeated bout effect of typical lower body strength training sessions on sub-maximal running performance and hormonal response

PURPOSE

This study examined the effects of two typical strength training sessions performed 1 week apart (i.e. repeated bout effect) on sub-maximal running performance and hormonal.

METHODS

Fourteen resistance-untrained men (age 24.0 ± 3.9 years; height 1.83 ± 0.11 m; body mass 77.4 ± 14.0 kg; VOpeak 48.1 ± 6.1 M kg(-1) min(-1)) undertook two bouts of high-intensity strength training sessions (i.e. six-repetition maximum). Creatine kinase (CK), delayed-onset muscle soreness (DOMS), counter-movement jump (CMJ) as well as concentrations of serum testosterone, cortisol and testosterone/cortisol ratio (T/C) were examined prior to and immediately post, 24 (T24) and 48 (T48) h post each strength training bout. Sub-maximal running performance was also conducted at T24 and T48 of each bout.

RESULTS

When measures were compared between bouts at T48, the degree of elevation in CK (-58.4 ± 55.6 %) and DOMS (-31.43 ± 42.9 %) and acute reduction in CMJ measures (4.1 ± 5.4 %) were attenuated (p < 0.05) following the second bout. Cortisol was increased until T24 (p < 0.05) although there were no differences between bouts and no differences were found for testosterone and T/C ratio (p > 0.05). Sub-maximal running performance was impaired until T24, although changes were not attenuated following the second bout.

CONCLUSIONS

The initial bout appeared to provide protection against a number of muscle damage indicators suggesting a greater need for recovery following the initial session of typical lower body resistance exercises in resistance-untrained men although sub-maximal running should be avoided following the first two sessions.

The direct effect of specific training and walking on bone metabolic markers in young adults with peak bone mass

As a prevention, a physically active lifestyle including the performance of weight-bearing exercises is important to enhance and maintain bone mineral content. Fifty young women were selected for the study. Twenty-five women carried out a specific training directed by a physiotherapist in the training group (TG), while 25 women were walking for 60 minutes in the control group (CG). Total and bone-specific alkaline phosphatase (ALP and BALP) and C-terminal cross-linked telopeptide (CTX) levels were measured at the beginning and at the end of exercise. The most remarkable change was seen in CTX levels (TG -28.89%, p < 0.001; CG -52.54%, p < 0.001), and there was also a significant difference in the values of CTX between TG and CG (p = 0.012). Therefore, walking more significantly reduced the level of CTX than special exercise. The decrease of BALP in TG was considerable but not significant (TG -4.63%, p = 0.091), while BALP levels dropped significantly in CG (-7.65%, p = 0.011), and there was a non-significant difference between the two groups (p = 0.22). Regarding the ALP level, a significant reduction was detected in TG and CG (-6.84%, p < 0.001 vs. -4.57%, p < 0.001). This study reveals that the 60-minute, middle-intensity training and the brisk walking have an immediate effect on bone metabolic markers.

The clinical utility of bone marker measurements in osteoporosis

Osteoporosis is characterised by low bone mass and structural deterioration of bone tissue, resulting in increased fragility and susceptibility to fracture. Osteoporotic fractures are a significant cause of morbidity and mortality. Direct medical costs from such fractures in the UK are currently estimated at over two billion pounds per year, resulting in a substantial healthcare burden that is expected to rise exponentially due to increasing life expectancy. Currently bone mineral density is the WHO standard for diagnosis of osteoporosis, but poor sensitivity means that potential fractures will be missed if it is used alone. During the past decade considerable progress has been made in the identification and characterisation of specific biomarkers to aid the management of metabolic bone disease. Technological developments have greatly enhanced assay performance producing reliable, rapid, non-invasive cost effective assays with improved sensitivity and specificity. We now have a greater understanding of the need to regulate pre-analytical sample collection to minimise the effects of biological variation. However, bone turnover markers (BTMs) still have limited clinical utility. It is not routinely recommended to use BTMs to select those at risk of fractures, but baseline measurements of resorption markers are useful before commencement of anti-resorptive treatment and can be checked 3–6 months later to monitor response and adherence to treatment. Similarly, formation markers can be used to monitor bone forming agents. BTMs may also be useful when monitoring patients during treatment holidays and aid in the decision as to when therapy should be recommenced. Recent recommendations by the Bone Marker Standards Working Group propose to standardise research and include a specific marker of bone resorption (CTX) and bone formation (P1NP) in all future studies. It is hoped that improved research in turn will lead to optimised markers for the clinical management of osteoporosis and other bone diseases.

β-Hydroxy-β-methylbutyrate free acid reduces markers of exercise-induced muscle damage and improves recovery in resistance-trained men

The purpose of the present study was to determine the effects of short-term supplementation with the free acid form of b-hydroxyb-methylbutyrate (HMB-FA) on indices of muscle damage, protein breakdown, recovery and hormone status following a high-volume resistance training session in trained athletes. A total of twenty resistance-trained males were recruited to participate in a high-volume resistance training session centred on full squats, bench presses and dead lifts. Subjects were randomly assigned to receive either 3 g/d of HMB-FA or a placebo. Immediately before the exercise session and 48 h post-exercise, serum creatine kinase (CK), urinary 3-methylhistadine (3-MH), testosterone, cortisol and perceived recovery status (PRS) scale measurements were taken. The results showed that CK increased to a greater extent in the placebo (329%) than in the HMB-FA group (104%) (P¼0·004, d ¼ 1·6). There was also a significant change for PRS, which decreased to a greater extent in the placebo (9·1 (SEM 0·4) to 4·6 (SEM 0·5)) than in the HMB-FA group (9·1 (SEM 0·3) to 6·3 (SEM 0·3)) (P¼0·005, d ¼ 20·48). Muscle protein breakdown, measured by 3-MH analysis, numerically decreased with HMB-FA supplementation and approached significance (P¼0·08, d ¼ 0·12). There were no acute changes in plasma total or free testosterone, cortisol or C-reactive protein. In conclusion, these results suggest that an HMB-FA supplement given to trained athletes before exercise can blunt increases in muscle damage and prevent declines in perceived readiness to train following a high-volume, muscle-damaging resistance-training session.

Acute bone marker responses to whole-body vibration and resistance exercise in young women

Whole-body vibration (WBV) augments the musculoskeletal effects of resistance exercise (RE). However, its acute effects on bone turnover markers (BTM) have not been determined. This study examined BTM responses to acute high-intensity RE and high-intensity RE with WBV (WBV+RE) in young women (n=10) taking oral contraceptives in a randomized, crossover repeated measures design. WBV+RE exposed subjects to 5 one-minute bouts of vibration (20 Hz, 3.38 peak-peak displacement, separated by 1 min of rest) before RE. Fasting blood samples were obtained before (Pre), immediately after WBV (PostVib), immediately after RE (IP), and 30-min after RE (P30). Bone alkaline phosphatase did not change at any time point. Tartrate-resistant acid phosphatase 5b significantly increased (p<0.05) from the Pre to PostVib, then decreased from IP to P30 for both conditions. C-terminal telopeptide of type I collagen (CTX) significantly decreased (p<0.05) from Pre to PostVib and from Pre to P30 only for WBV+RE. WBV+RE showed a greater decrease in CTX than RE (-12.6% ± 4.7% vs -1.13% ± 3.5%). In conclusion, WBV was associated with acute decreases in CTX levels not elicited with RE alone in young women.

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

Individuals 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 ± 4y (mean ±SD) completed two, counterbalanced, 8d trials. After 3d on a standardised diet, participants performed 60 min of treadmill running at 65% VO(2max) 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 (β-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 β-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 1h post-exercise. At 3h 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 β-CTX during early recovery, but having no effect on changes in bone formation markers. The reduced duration of the β-CTX response with fasting was not fully explained by changes in PTH, OPG, leptin or ghrelin.