The Bone Metabolic Response to Exercise and Nutrition

An Opinion on the Interpretation of Bone Turnover Markers Following Acute Exercise or Nutrition Intervention and Considerations for Applied Research

It is important for athlete and public health that we continue to develop our understanding of the effects of exercise and nutrition on bone health. Bone turnover markers (BTMs) offer an opportunity to accelerate the progression of bone research by revealing a bone response to exercise and nutrition stimuli far more rapidly than current bone imaging techniques. However, the association between short-term change in the concentration of BTMs and long-term bone health remains ambiguous. Several other limitations also complicate the translation of acute BTM data to applied practice. Importantly, several incongruencies exist between the effects of exercise and nutrition stimuli on short-term change in BTM concentration compared with long-term bone structural outcomes to similar stimuli. There are many potential explanations for these inconsistencies, including that short-term study designs fail to encompass a full remodeling cycle. The current article presents the opinion that data from relatively acute studies measuring BTMs may not be able to reliably inform applied practice aiming to optimize bone health. There are important factors to consider when interpreting or translating BTM data and these are discussed.

Influence of Menstrual Cycle and Oral Contraceptive Phases on Bone (re)modelling Markers in Response to Interval Running

To explore how sex hormone fluctuations may affect bone metabolism, this study aimed to examine P1NP and β-CTX-1 concentrations across the menstrual and oral contraceptive (OC) cycle phases in response to running. 17β-oestradiol, progesterone, P1NP and β-CTX-1 were analysed pre- and post-exercise in eight eumenorrheic females in the early-follicular, late-follicular, and mid-luteal phases, while 8 OC users were evaluated during the withdrawal and active pill-taking phases. The running protocol consisted of 8 × 3min treadmill runs at 85% of maximal aerobic speed. 17β-oestradiol concentrations (pg·ml-1) were lower in early-follicular (47.22 ± 39.75) compared to late-follicular (304.95 ± 235.85;p =  < 0.001) and mid-luteal phase (165.56 ± 80.6;p = 0.003) and higher in withdrawal (46.51 ± 44.09) compared to active pill-taking phase (10.88 ± 11.24;p < 0.001). Progesterone (ng·ml-1) was higher in mid-luteal (13.214 ± 4.926) compared to early-follicular (0.521 ± 0.365; p < 0.001) and late-follicular phase (1.677 ± 2.586;p < 0.001). In eumenorrheic females, P1NP concentrations (ng·ml-1) were higher in late-follicular (69.97 ± 17.84) compared to early-follicular (60.96 ± 16.64;p = 0.006;) and mid-luteal phase (59.122 ± 11.77;p = 0.002). β-CTX-1 concentrations (ng·ml-1) were lower in mid-luteal (0.376 ± 0.098) compared to late-follicular (0.496 ± 0.166; p = 0.001) and early-follicular phase (0.452 ± 0.148; p = 0.039). OC users showed higher post-exercise P1NP concentrations in withdrawal phase (61.75 ± 8.32) compared to post-exercise in active pill-taking phase (45.45 ± 6;p < 0.001). Comparing hormonal profiles, post-exercise P1NP concentrations were higher in early-follicular (66.91 ± 16.26;p < 0.001), late-follicular (80.66 ± 16.35;p < 0.001) and mid-luteal phases (64.57 ± 9.68;p = 0.002) to active pill-taking phase. These findings underscore the importance of studying exercising females with different ovarian hormone profiles, as changes in sex hormone concentrations affect bone metabolism in response to running, showing a higher post-exercise P1NP concentrations in all menstrual cycle phases compared with active pill-taking phase of the OC cycle.

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 (CTXI) 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.

Identifying and Analyzing Low Energy Availability in Athletes: The Role of Biomarkers and Red Blood Cell Turnover

Low energy availability (LEA) is a growing concern that can lead to several problems for athletes. However, adaptation to LEA occurs to maintain balance over time, making diagnosis difficult. In this review, we categorize LEA into two phases: the initial phase leading to adaptation and the phase in which adaptation is achieved and maintained. We review the influence of LEA on sports performance and health and discuss biomarkers for diagnosing LEA in each phase. This review also proposes future research topics for diagnosing LEA, with an emphasis on the recently discovered association between red blood cell turnover and LEA.

One Week of Single-Leg Immobilization Lowers Muscle Connective Protein Synthesis Rates in Healthy, Young Adults

PURPOSE

Short periods of limb immobilization lower myofibrillar protein synthesis rates. Within skeletal muscle, the extracellular matrix of connective proteins is recognized as an important factor determining the capacity to transmit contractile force. Little is known regarding the impact of immobilization and subsequent recovery on muscle connective protein synthesis rates. This study examined the impact of 1 wk of leg immobilization and 2 wk of subsequent ambulant recovery on daily muscle connective protein synthesis rates.

METHODS

Thirty healthy, young (24 ± 5 yr) men were subjected to 7 d of one-legged knee immobilization followed by 14 d of ambulant recovery. Deuterium oxide ingestion was applied over the entire period, and muscle biopsy samples were collected before immobilization, after immobilization, and after recovery to measure muscle connective protein synthesis rates and mRNA expression of key extracellular matrix proteins (collagen I, collagen III), glycoproteins (fibronectin, tenascin-C), and proteoglycans (fibromodulin, and decorin). A two-way repeated-measures (time-leg) ANOVA was used to compare changes in muscle connective protein synthesis rates during immobilization and recovery.

RESULTS

During immobilization, muscle connective protein synthesis rates were lower in the immobilized (1.07 ± 0.30%·d -1 ) compared with the nonimmobilized (1.48 ± 0.44%·d -1 ; P < 0.01) leg. When compared with the immobilization period, connective protein synthesis rates in the immobilized leg increased during subsequent recovery (1.48 ± 0.64%·d -1 ; P < 0.01). After recovery, skeletal muscle collagen I, collagen III, fibronectin, fibromodulin, and decorin mRNA expression increased when compared with the postimmobilization time point (all P < 0.001).

CONCLUSIONS

One week of leg immobilization lowers muscle connective protein synthesis rates. Muscle connective protein synthesis rates increase during subsequent ambulant recovery, which is accompanied by increased mRNA expression of key extracellular matrix proteins.

Hormonal contraceptive use is associated with altered bone structural and metabolic responses to military training in women: An observational cohort study

Military training increases tibial density and size. Female sex hormones may influence the adaption of bone to loading, but it is unknown if women using different hormonal contraceptives adapt similarly to military training. One hundred and sixteen women (57 women not using hormonal contraceptives [non-users], 38 combined oral contraceptive pill [COCP] users, 21 depot medroxyprogesterone acetate [DMPA] users) completed this study. Tibial volumetric bone mineral density (vBMD) and geometry were measured by peripheral quantitative computed tomography (4 %, 14 %, 38 %, and 66 % sites) at the start (week 1) and end (week 14) of British Army basic training. Circulating markers of bone and calcium metabolism were measured at weeks 1, 2, 4, 6, 10, and 14. Training increased trabecular vBMD at the 4 % site, periosteal perimeter at the 14 % and 66 % sites, and total area, cortical area, cortical thickness, and bone strength at all sites (0.1 to 1.6 %, p ≤ 0.009), with no differences between hormonal contraceptive groups (p ≥ 0.127). Trabecular vBMD increased at the 14 % site in non-users (0.8 %, p = 0.005), but not in COCP or DMPA users (p ≥ 0.205). Periosteal perimeter increased at the 38 % site in COCP (0.4 %, p < 0.001) and DMPA (0.5 %, p < 0.001) users, but not in non-users (p = 0.058). Training had no effect on periosteal perimeter at the 4 % site or cortical vBMD or endosteal perimeter at any site (p ≥ 0.168). βCTX decreased and PINP increased during training with no difference between hormonal contraceptive groups. Training increased iPTH in non-users, but not COCP or DMPA users. Hormonal contraceptives may exert site-specific effects on the mechanobiology of bone, with higher endogenous oestradiol promoting trabecularisation and inhibiting periosteal expansion in non-users compared with hormonal contraceptive users.

Load carriage exercise increases calcium absorption and retention in healthy young women

Aerobic exercise reduces circulating ionized Ca (iCa) and increases parathyroid hormone (PTH), but the cause and consequences on Ca handling are unknown. The objective of this study was to determine the effects of strenuous exercise on Ca kinetics using dual stable Ca isotopes. Twenty-one healthy women (26.4 ± 6.7 yr) completed a randomized, crossover study entailing two 6-d iterations consisting of either 60 min of treadmill walking at 65% VO2max wearing a vest weighing 30% body weight on study days 1, 3, and 5 (exercise [EX]), or a rest iteration (rest [REST]). On day 1, participants received intravenous 42Ca and oral 44Ca. Isotope ratios were determined by thermal ionization mass spectrometry. Kinetic modeling determined fractional Ca absorption (FCA), Ca deposition (Vo+), resorption (Vo-) from bone, and balance (Vbal). Circulating PTH and iCa were measured before, during, and after each exercise/rest session. Data were analyzed by paired t-test or linear mixed models using SPSS. iCa decreased and PTH increased (P < .001) during each EX session and were unchanged during REST. On day 1, urinary Ca was lower in the EX pool (25 ± 11 mg) compared to REST (38 ± 16 mg, P = .001), but did not differ over the full 24-h collection (P > .05). FCA was greater during EX (26.6 ± 8.1%) compared to REST (23.9 ± 8.3%, P < .05). Vbal was less negative during EX (-61.3 ± 111 mg) vs REST (-108 ± 23.5 mg, P < .05), but VO+ (574 ± 241 vs 583 ± 260 mg) and VO- (-636 ± 243 vs -692 ± 252 mg) were not different (P > .05). The rapid reduction in circulating iCa may be due to a change in the miscible Ca pool, resulting in increased PTH and changes in intestinal absorption and renal Ca handling that support a more positive Ca balance.

Effects of acute- and long-term aerobic exercises at different intensities on bone in mice

INTRODUCTION

Exercise intensity determines the benefits of aerobic exercise. Our objectives were, in aerobic exercise at different intensities, to determine (1) changes in bone metabolism-related genes after acute exercise and (2) changes in bone mass, strength, remodeling, and bone formation-related proteins after long-term exercise.

MATERIALS AND METHODS

Total 36 male C57BL/6J mice were divided into a control group and exercise groups at 3 different intensities: low, moderate, or high group. Each exercise group was assigned to acute- or long-term exercise groups. Tibias after acute exercise were evaluated by real-time PCR analysis. Furthermore, hindlimbs of long-term exercise were assessed by micro-CT, biomechanical, histological, and immunohistochemical analyses.

RESULTS

Acute moderate-intensity exercise decreased RANKL level as bone resorption marker, whereas low- and high-intensity exercise did not alter it. Additionally, only long-term exercise at moderate intensity increased bone mass and strength. Moderate-intensity exercise promoted osteoblast activity and suppressed osteoclast activity. After low- and high-intensity exercise, osteoblast and osteoclast activity were unchanged. An increase in the number of β-catenin-positive cells and a decrease in sclerostin-positive cells were observed in the only moderate group.

CONCLUSION

These results showed that moderate-intensity exercise can inhibit bone resorption earlier, and long-term exercise can increase bone mass and strength through promoted bone formation via the Wnt/β-catenin activation. High-intensity exercise, traditionally considered better for bone, may fail to stimulate bone remodeling, leading to no change in bone mass and strength. Our findings suggest that moderate-intensity exercise, neither too low nor high, can maintain bone health.

Idiosyncratic bone responses to blood flow restriction exercise: new insights and future directions

Applying blood flow restriction (BFR) during low-load exercise induces beneficial adaptations of the myotendinous and neuromuscular systems. Despite the low mechanical tension, BFR exercise facilitates a localized hypoxic environment and increase in metabolic stress, widely regarded as the primary stimulus for tissue adaptations. First evidence indicates that low-load BFR exercise is effective in promoting an osteogenic response in bone, although this has previously been postulated to adapt primarily during high-impact weight-bearing exercise. Besides studies investigating the acute response of bone biomarkers following BFR exercise, first long-term trials demonstrate beneficial adaptations in bone in both healthy and clinical populations. Despite the increasing number of studies, the physiological mechanisms are largely unknown. Moreover, heterogeneity in methodological approaches such as biomarkers of bone metabolism measured, participant and study characteristics, and time course of measurement renders it difficult to formulate accurate conclusions. Furthermore, incongruity in the methods of BFR application (e.g., cuff pressure) limits the comparability of datasets and thus hinders generalizability of study findings. Appropriate use of biomarkers, effective BFR application, and befitting study design have the potential to progress knowledge on the acute and chronic response of bone to BFR exercise and contribute toward the development of a novel strategy to protect or enhance bone health. Therefore, the purpose of the present synthesis review is to 1) evaluate current mechanistic evidence; 2) discuss and offer explanations for similar and contrasting data findings; and 3) create a methodological framework for future mechanistic and applied research.

High-Protein Diets during either Resistance or Concurrent Training Have No Detrimental Effect on Bone Parameters in Resistance-Trained Males

BACKGROUND

The effects of combining resistance training (RT) and concurrent training (CT; resistance + endurance training) with varied protein doses on bone measures remain poorly understood. Hence, we conducted a comparison of the impacts of two high-protein diets (1.6 or 3.2 g kg-1 d-1) over 16 weeks in resistance-trained males, either with CT or RT alone.

METHODS

A total of forty-eight males, all of whom were resistance-trained, had the following demographics: 26.6 ± 6 years, body mass index: 25.6 ± 2.9 kg m-2 administered either 3.2 g kg-1 d-1 protein (CT2; n = 12; RT2; n = 12) or 1.6 g kg-1 d-1 protein (CT1; n = 12; RT1; n = 12) during 16 weeks (four sessions·w-1). Bone parameters were assessed pre- and post-intervention.

RESULTS

There was no significant interaction between the intervention group and time for the legs, arms, ribs, or pelvis area BMC and BMD (p > 0.05). For the BMD of the pelvis and the BMC of the right ribs, however, there were significant time effects noted (p < 0.05). Furthermore, there was a significant interaction between the intervention group and time in the lumbar and thoracic spines, with a particular time effect noted for the thoracic spine region (p < 0.05). The regional differences in skeletal responses to the intervention are highlighted by these data.

CONCLUSION

Our findings show that the intake of two high-protein diets combined with RT and CT during 16 weeks had no adverse effects on bone tissue parameters. While these findings indicate that protein intake between 2 and 3 times the current RDI does not promote bone demineralization when consumed in conjunction with exercise, future studies investigating the long-term effects of chronic high protein intake on bone tissue health are warranted.

Does adding exercise or physical activity to pharmacological osteoporosis therapy in patients with increased fracture risk improve bone mineral density and lower fracture risk? A systematic review and meta-analysis

This prospectively registered systematic review and meta-analysis examines whether exercise (EX) training has an additive effect to osteoanabolic and/or antiresorptive pharmacological therapy (PT) in people with osteoporosis on bone mineral density (BMD), bone turnover markers (BTMs), fracture healing, and fractures. Four databases (inception to 6 May 2022), 5 trial registries, and reference lists were searched. Included were randomized controlled trials comparing the effect of EX + PT vs. PT with regard to BMD, BTM, fracture healing, and fractures. Risk of bias was assessed using the Cochrane RoB2 and certainty of evidence by the GRADE approach. Random-effects meta-analysis with Hartung-Knapp-Sidik-Jonkman adjustment was used to estimate standardized mean differences and 95% confidence intervals. Out of 2593 records, five RCTs with 530 participants were included. Meta-analysis showed with very low certainty evidence and wide confidence intervals that EX + PT compared to PT had larger effect sizes for BMD at 12 months at the hip (SMD [95%CI]: 0.18 [- 1.71; 2.06], n = 3 studies), tibia (0.25 [- 4.85; 5.34], n = 2), lumbar spine (0.20 [- 1.15; 1.55], n = 4), and forearm (0.05 [- 0.35; 0.46], n = 3), but not femoral neck (- 0.03 [- 1.80; 1.75], n = 3). Furthermore, no improvement was revealed for BTM such as bone ALP (- 0.68 [- 5.88; 4.53], n = 3), PINP (- 0.74 [- 10.42; 8.93], n = 2), and CTX-I (- 0.69 [- 9.61; 8.23], n = 2), but with very wide confidence intervals. Three potentially relevant ongoing trials were identified via registries. No data were found for fracture healing or fracture outcomes. It remains unclear whether EX has an additive impact to PT in people with osteoporosis. High-quality, adequately powered, targetted RCTs are required. PROTOCOL REGISTRATION: PROSPERO CRD42022336132.

The pathogenesis of post-stroke osteoporosis and the role oxidative stress plays in its development

Cardiovascular disease and osteoporotic fractures (OF) are the main diseases affecting the health of middle-aged and elderly people. With the gradual increase of population aging in China and even the world, the incidence of the two and the prevalence of high-risk groups are also showing a continuous upward trend. The relationship between the two, especially the impact of cardiovascular disease on the risk and prognosis of OF, has attracted more and more attention. Therefore, it is of great significance to fully understand the pathogenesis of cardiovascular and cerebrovascular diseases and the resulting osteoporosis and to provide targeted interventions to prevent the occurrence of diseases and fractures. This article reviews the relationship between one of the Cardiovascular disease-stroke and related therapeutic drugs and the risk of OF, and the role of oxidative stress in its pathophysiological mechanism by reviewing relevant domestic and foreign literature in recent years, in order to gain a more comprehensive understanding of the association between stroke and OF, and then provide a basis and reference for screening high-risk groups of fractures and reducing the burden on the health system caused by the disease.

P1NP and β-CTX-1 Responses to a Prolonged, Continuous Running Bout in Young Healthy Adult Males: A Systematic Review with Individual Participant Data Meta-analysis

BACKGROUND

Circulating biomarkers of bone formation and resorption are widely used in exercise metabolism research, but their responses to exercise are not clear. This study aimed to quantify group responses and inter-individual variability of P1NP and β-CTX-1 after prolonged, continuous running (60-120 min at 65-75% V̇O2max) in young healthy adult males using individual participant data (IPD) meta-analysis.

METHODS

The protocol was designed following PRISMA-IPD guidelines and was pre-registered on the Open Science Framework prior to implementation ( https://osf.io/y69nd ). Changes in P1NP and β-CTX-1 relative to baseline were measured during, immediately after, and in the hours and days following exercise. Typical hourly and daily variations were estimated from P1NP and β-CTX-1 changes relative to baseline in non-exercise (control) conditions. Group responses and inter-individual variability were quantified with estimates of the mean and standard deviation of the difference, and the proportion of participants exhibiting an increased response. Models were conducted within a Bayesian framework with random intercepts to account for systematic variation across studies.

RESULTS

P1NP levels increased during and immediately after running, when the proportion of response was close to 100% (75% CrI: 99 to 100%). P1NP levels returned to baseline levels within 1 h and over the next 4 days, showing comparable mean and standard deviation of the difference with typical hourly (0.1 ± 7.6 ng·mL-1) and daily (- 0.4 ± 5.7 ng·mL-1) variation values. β-CTX-1 levels decreased during and up to 4 h after running with distributions comparable to typical hourly variation (- 0.13 ± 0.11 ng·mL-1). There was no evidence of changes in β-CTX-1 levels during the 4 days after the running bout, when distributions were also similar between the running data and typical daily variation (- 0.03 ± 0.10 ng·mL-1).

CONCLUSION

Transient increases in P1NP were likely biological artefacts (e.g., connective tissue leakage) and not reflective of bone formation. Comparable small decreases in β-CTX-1 identified in both control and running data, suggested that these changes were due to the markers' circadian rhythm and not the running intervention. Hence, prolonged continuous treadmill running did not elicit bone responses, as determined by P1NP and β-CTX-1, in this population.

Methodology for studying Relative Energy Deficiency in Sport (REDs): a narrative review by a subgroup of the International Olympic Committee (IOC) consensus on REDs

In the past decade, the study of relationships among nutrition, exercise and the effects on health and athletic performance, has substantially increased. The 2014 introduction of Relative Energy Deficiency in Sport (REDs) prompted sports scientists and clinicians to investigate these relationships in more populations and with more outcomes than had been previously pursued in mostly white, adolescent or young adult, female athletes. Much of the existing physiology and concepts, however, are either based on or extrapolated from limited studies, and the comparison of studies is hindered by the lack of standardised protocols. In this review, we have evaluated and outlined current best practice methodologies to study REDs in an attempt to guide future research.This includes an agreement on the definition of key terms, a summary of study designs with appropriate applications, descriptions of best practices for blood collection and assessment and a description of methods used to assess specific REDs sequelae, stratified as either Preferred, Used and Recommended or Potential Researchers can use the compiled information herein when planning studies to more consistently select the proper tools to investigate their domain of interest. Thus, the goal of this review is to standardise REDs research methods to strengthen future studies and improve REDs prevention, diagnosis and care.

The effects of community-based exercise modalities and volume on musculoskeletal health and functions in elderly people

The effects of different muscle loading exercise (MLEX) modes and volume on musculoskeletal health is not well-studied in older populations. Aim: Therefore, this study aimed to compare the effects of community-based MLEX modalities and volume on musculoskeletal health in elderly people. Methods: Elderly men (n = 86) and women (n = 170), age 50-82 years old, were assigned to the sedentary (SE, n = 60), muscle strengthening exercise (MSE, n = 71), aerobic exercise (AE, n = 62) and Tai Chi exercise (TCE, n = 63) groups, based on > 2 years of exercise history. Exercise volume was compared between "Minimum" ("Min" < 60 min/week), "Low" (60-120 min/week). "Moderate" (121-239 min/week) and "High" (240-720 min/week) volumes. Results: All three modes of MLEX were associated with lower percentage of body fat (BF%) and higher percentage of lean body mass (LBM%, p = 0.003 main effect of group, and p = 0.002 main effect of volume for both BF% and LBM%), but not with higher bone mineral density (BMD, total body, lumbar spine, total hip and neck of femur), than SE. TCE had a distinct advantage in trunk flexibility (p = 0.007 with MSE, p = 0.02 with AE, and p = 0.01 with SE), and both TCE (p = 0.03) and AE (p = 0.03) performed better than SE in the one-leg stand balance test. Isometric strength and throwing speed and peak power with a 2 kg power ball were higher in the MLEX than SE groups (p = 0.01), in the ranking order of MSE, AE and TCE. However, there was no difference in handgrip strength performance between the MLEX groups, which performed better than the SE participants. Accumulating >120 min/week of MLEX can promote body composition health and muscle functions, but 60 min/week of MSE alone may have equal or better outcomes in these parameters. Conclusion: Community-based MLEX classes may be used to mitigate age-related chronic disease that are associated with body composition and muscular functions.

Exerkines and redox homeostasis

Exercise physiology has gained increasing interest due to its wide effects to promote health. Recent years have seen a growth in this research field also due to the finding of several circulating factors that mediate the effects of exercise. These factors, termed exerkines, are metabolites, growth factors, and cytokines secreted by main metabolic organs during exercise to regulate exercise systemic and tissue-specific effects. The metabolic effects of exerkines have been broadly explored and entail a promising target to modulate beneficial effects of exercise in health and disease. However, exerkines also have broad effects to modulate redox signaling and homeostasis in several cellular processes to improve stress response. Since redox biology is central to exercise physiology, this review summarizes current evidence for the cross-talk between redox biology and exerkines actions. The role of exerkines in redox biology entails a response to oxidative stress-induced pathological cues to improve health outcomes and to modulate exercise adaptations that integrate redox signaling.

Sclerostin decreases in regular swimmers after ice swimming and is associated with meteorin-like protein serum levels

Introduction: Cold and exercise are two important stimuli affecting the secretion of osteokines and adipomyokines, which often occur simultaneously. However, few studies have investigated the changes in osteokines and adipomyokines induced by exercise during severe cold and their corresponding associations. Therefore, this study aimed to investigate the changes in sclerostin and meteorin-like (metrnl) protein before and after cold exercise (ice swimming [IS]) and observe their correlation. Methods: For this, 56 daily ice swimmers' data were included in this study. Serum sclerostin and metrnl were measured 30 min before IS and 30 min after. The fat mass, visceral fat area, fat-free mass, skeletal muscle mass, lumbar spine, and femoral neck bone mineral density of the ice swimmers were measured. Results: After IS, sclerostin exhibited significant decreases, whereas metrnl showed no significant change. In addition, the baseline level of sclerostin and the decrease in sclerostin were positively correlated with serum metrnl after adjusting for age, gender, and body composition indicators. Discussion: IS caused a significant decrease in sclerostin but did not affect metrnl. Furthermore, the associations between sclerostin and metrnl suggested a correlation between osteokines and adipomyokines; this encourages future exploration of the interconnection between bone, muscle, and fat, which will be beneficial for identifying potential common therapeutic targets for diseases such as osteoporosis, sarcopenia, and obesity.

The effects of water-based exercise on body composition: A systematic review and meta-analysis

AIMS

This study aimed to investigate the effects of water-based exercise (WBE) on body composition.

METHODS

Trials published up to October 28, 2022 were searched using the PubMed, EMBASE, Web of Science, Cochrane, Scopus, and Ovid databases. Randomized controlled trials of healthy adults published in English, comparing WBE and control groups, were included. Other studies with different research designs and participants with medical diagnoses were excluded. The main outcome measures were body weight (BW), body fat mass (BFM), body fat percentage (BFP), lean mass (LM), and skeletal muscle mass (SMM).

RESULTS

Overall, 17,458 potential studies were identified. After a closer inspection, 79 full-length articles were considered for further screening. Finally, 20 studies, involving 565 participants, were included in the meta-analysis. The WBE was beneficial in reducing BW, BFM, and BFP and increasing LM and SMM. Subgroup analyses were conducted based on different exercise intensities and times per week. Moderate- or moderate-vigorous-intensity exercise helped improve body composition, while lower-intensity WBE or aquatic high-intensity interval training (HIIT) seemed less helpful. Training for <120 min/week was insufficient to improve body composition. Training for >120 min/week was associated with improvements in body composition.

CONCLUSIONS

Moderate- or moderate-vigorous-intensity WBE helps improve body composition. Adults are encouraged to exercise for >120 min/week.

Bone turnover following high-impact exercise is not modulated by collagen supplementation in young men: A randomized cross-over trial

INTRODUCTION

We assessed whether collagen supplementation augments the effects of high-impact exercise on bone turnover and whether a higher exercise frequency results in a greater benefit for bone metabolism.

METHODS

In this randomized, cross-over trial, 14 healthy males (age 24 ± 4 y, BMI 22.0 ± 2.1 kg/m²) performed 5-min of high-impact exercise once (JUMP+PLA and JUMP+COL) or twice daily (JUMP2+COL2) during a 3-day intervention period, separated by a 10-day wash out period. One hour before every exercise bout participants ingested 20 g hydrolysed collagen (JUMP+COL and JUMP2+COL2) or a placebo control (JUMP+PLA). Blood markers of bone formation (P1NP) and resorption (CTXI) were assessed in the fasted state before the ingestion of the initial test drinks and 24, 48, and 72 h thereafter. In JUMP+PLA and JUMP+COL, additional blood samples were collected in the postprandial state at 1, 2, 3, 4, 5 and 13 h after ingestion of the test drink.

RESULTS

In the postprandial state, serum P1NP concentrations decreased marginally from 99 ± 37 to 93 ± 33 ng/mL in JUMP+COL, and from 97 ± 32 to 92 ± 31 ng/mL in JUMP+PLA, with P1NP levels having returned to baseline levels after 13 h (time-effect, P = 0.053). No differences in serum P1NP concentrations were observed between JUMP+PLA and JUMP+COL (time x treatment, P = 0.58). Serum CTX-I concentrations showed a ~ 50 % decline (time, P < 0.001) in the postprandial state in JUMP+COL (0.9 ± 0.3 to 0.4 ± 0.2 ng/mL) and JUMP+PLA (0.9 ± 0.3 to 0.4 ± 0.2 ng/mL), with no differences between treatments (time x treatment, P = 0.17). Fasted serum P1NP concentrations increased ~8 % by daily jumping exercise (time-effect, P < 0.01), with no differences between treatments (time x treatment, P = 0.71). Fasted serum CTX-I concentrations did not change over time (time-effect, P = 0.41) and did not differ between treatments (time x treatment, P = 0.58).

CONCLUSIONS

Five minutes of high-impact exercise performed daily stimulates bone formation during a 3-day intervention period. This was indicated by an increase in fasted serum P1NP concentrations, rather than an acute increase in post-exercise serum P1NP concentrations. Collagen supplementation or an increase in exercise frequency does not further increase serum P1NP concentrations. The bone resorption marker CTX-I was not affected by daily short-duration high-impact exercise with or without concurrent collagen supplementation.

Current risks factors and emerging biomarkers for bone stress injuries in military personnel

INTRODUCTION

Bone stress injuries (BSIs) have plagued the military for over 150 years; they afflict around 5 to 10% of military recruits, more so in women, and continue to place a medical and financial burden on defence. While the tibia generally adapts to the rigours of basic military training, the putative mechanisms for bone maladaptation are still unclear.

METHODS

This paper provides a review of the published literature on current risk factors and emerging biomarkers for BSIs in military personnel; the potential for biochemical markers of bone metabolism to monitor the response to military training; and, the association of novel biochemical 'exerkines' with bone health.

RESULTS

The primary risk factor for BSI in military (and athletic) populations is too much training, too soon. Appropriate physical preparation before training will likely be most protective, but routine biomarkers will not yet identify those at risk. Nutritional interventions will support a bone anabolic response to training, but exposure to stress, sleep loss, and medication is likely harmful to bone. Monitoring physiology using wearables-ovulation, sleep and stress-offer potential to inform prevention strategies.

CONCLUSIONS

The risk factors for BSIs are well described, but their aetiology is very complex particularly in the multi-stressor military environment. Our understanding of the skeletal responses to military training is improving as technology advances, and potential biomarkers are constantly emerging, but sophisticated and integrated approaches to prevention of BSI are warranted.

Relationship between Football-Specific Training Characteristics and Tibial Bone Adaptation in Male Academy Football Players

We examined the relationship between football-specific training and changes in bone structural properties across a 12-week period in 15 male football players aged 16 years (Mean ± 1 SD = 16.6 ± 0.3 years) that belonged to a professional football academy. Tibial scans were performed at 4%, 14% and 38% sites using peripheral quantitative computed tomography immediately before and 12 weeks after increased football-specific training. Training was analysed using GPS to quantify peak speed, average speed, total distance and high-speed distance. Analyses were conducted with bias-corrected and accelerated bootstrapped 95% confidence intervals (BCa 95% CI). There were increases in bone mass at the 4% (mean ∆ = 0.15 g, BCa 95% CI = 0.07, 0.26 g, g = 0.72), 14% (mean ∆ = 0.04 g, BCa 95% CI = 0.02, 0.06 g, g = 1.20), and 38% sites (mean ∆ = 0.03 g, BCa 95% CI = 0.01, 0.05 g, g = 0.61). There were increases in trabecular density (4%), (mean ∆ = 3.57 mg·cm^-3, BCa 95% CI = 0.38, 7.05 mg·cm^-3, g = 0.53), cortical dentsity (14%) (mean ∆ = 5.08 mg·cm^-3, BCa 95% CI = 0.19, 9.92 mg·cm^-3, g = 0.49), and cortical density (38%) (mean ∆ = 6.32 mg·cm^-3, BCa 95% CI = 4.31, 8.90 mg·cm^-3, g = 1.22). Polar stress strain index (mean ∆ = 50.56 mm³, BCa 95% CI = 10.52, 109.95 mm³, g = 0.41), cortical area (mean ∆ = 2.12 mm², BCa 95% CI = 0.09, 4.37 mm², g = 0.48) and thickness (mean ∆ = 0.06 mm, BCa 95% CI = 0.01, 0.13 mm, g = 0.45) increased at the 38% site. Correlations revealed positive relationships between total distance and increased cortical density (38%) (r = 0.39, BCa 95% CI = 0.02, 0.66), and between peak speed and increased trabecular density (4%) (r = 0.43, BCa 95% CI = 0.03, 0.73). There were negative correlations between total (r = -0.21, BCa 95% CI = -0.65, -0.12) and high-speed distance (r = -0.29, BCa 95% CI = -0.57, -0.24) with increased polar stress strain index (38%). Results suggest that despite football training relating to increases in bone characteristics in male academy footballers, the specific training variables promoting adaptation over a 12-week period may vary. Further studies conducted over a longer period are required to fully elucidate the time-course of how certain football-specific training characteristics influence bone structural properties.

Effect of Yi Jin Jing exercise plus Elastic Band Resistance exercise on overall bone mineral density in postmenopausal women

OBJECTIVES

This work aimed to study the effects of Yi Jin Jing plus Elastic Band Resistance exercise on bone mineral density at all parts of the body and bone metabolism index levels in postmenopausal women.

DESIGN

Randomized controlled trial.

METHODS

Forty postmenopausal women were randomly assigned equally to the exercise or to the control group. The control group maintained their lifestyle behaviors unaltered, whereas the exercise group received  Yi Jin Jing plus Elastic Band Resistance exercise. The primary outcome was overall bone mineral density at each part, and the secondary one was bone metabolism indicator levels and bone mineral density on both sides.

RESULTS

The results after six months showed increased bone mineral density at all parts of the body in the exercise group (spine, P = 0.002; thighs, lumbar, and whole body, P < 0.05) and decreased bone mineral density in the control group (trunk, pelvis, and spine, P < 0.01). In particular, the decrease and increase were greater on the non-preferred (left) side than on the right side. As for bone metabolism indexes, β-Crosslaps levels reduced (P = 0.016) and a significant increase in 1,25-(OH)2-D3 (P < 0.001) can be observed in the exercise group.

CONCLUSIONS

The results suggested that Yi Jin Jing plus Elastic Band Resistance exercise could delay the overall decrease of bone mineral density in postmenopausal women, especially on the non-preferred side. It also increased bone formation metabolite levels and inhibited bone resorption metabolite levels.

Twelve weeks of a diet and exercise intervention alters the acute bone response to exercise in adolescent females with overweight/obesity

Introduction: Exercise and consumption of dairy foods have been shown to improve bone mineralization. However, little is known about the magnitude and timing of their synergistic effects on markers and regulators of bone metabolism in response to acute exercise in adolescent females with obesity, a population susceptible to altered bone metabolism and mineral properties. This study examined the influence of twelve weeks of exercise training and nutritional counselling on the bone biochemical marker response to acute exercise and whether higher dairy consumption could further influence the response. Methods: Thirty adolescent females (14.3 ± 2.0 years) with overweight/obesity (OW/OB) completed a 12-week lifestyle modification intervention involving exercise training and nutritional counselling. Participants were randomized into two groups: higher dairy intake (RDa; 4 servings/day; n = 14) or low dairy intake (LDa; 0-2 servings/d; n = 16). Participants performed one bout of plyometric exercise (5 circuits; 120 jumps) both pre- and post-intervention. Blood samples were taken at rest, 5 min and 1 h post-exercise. Serum sclerostin, osteocalcin (OC), osteoprotegerin (OPG), receptor activator nuclear factor kappa B ligand (RANKL), and C-terminal telopeptide of type 1 collagen (βCTX) concentrations were measured. Results: While there was an overall increase in sclerostin pre-intervention from pre to 5 min post-exercise (+11% p = 0.04), this response was significantly decreased post-intervention (-25%, p = 0.03) independent of dairy intake. The OPG:RANKL ratio was unresponsive to acute exercise pre-intervention but increased 1 h post-exercise (+2.6 AU; p < 0.001) post-intervention. Dairy intake did not further influence these absolute responses. However, after the 12-week intervention, the RDa group showed a decrease in the relative RANKL post-exercise response (-21.9%; p < 0.01), leading to a consistent increase in the relative OPG:RANKL ratio response, which was not the case in the LDa group. There was no influence of the intervention or dairy product intake on OC, OPG, or βCTX responses to acute exercise (p > 0.05). Conclusion: A lifestyle modification intervention involving exercise training blunts the increase in sclerostin and can augment the increase in OPG:RANKL ratio to acute exercise in adolescent females with OW/OB, while dairy product consumption did not further influence these responses.

The Impact of Acute Calcium Intake on Bone Turnover Markers during a Training Day in Elite Male Rowers

INTRODUCTION

Although an acute exercise session typically increases bone turnover markers (BTM), the impact of subsequent sessions and the interaction with preexercise calcium intake remain unclear despite the application to the "real-life" training of many competitive athletes.

METHODS

Using a randomized crossover design, elite male rowers ( n = 16) completed two trials, a week apart, consisting of two 90-min rowing ergometer sessions (EX1, EX2) separated by 150 min. Before each trial, participants consumed a high (CAL; ~1000 mg) or isocaloric low (CON; <10 mg) calcium meal. Biochemical markers including parathyroid hormone (PTH), serum ionized calcium (iCa) and BTMs (C-terminal telopeptide of type I collagen, osteocalcin) were monitored from baseline to 3 h after EX2.

RESULTS

Although each session caused perturbances of serum iCa, CAL maintained calcium concentrations above those of CON for most time points, 4.5% and 2.4% higher after EX1 and EX2, respectively. The decrease in iCa in CON was associated with an elevation of blood PTH ( P < 0.05) and C-terminal telopeptide of type I collagen ( P < 0.0001) over this period of repeated training sessions and their recovery, particularly during and after EX2. Preexercise intake of calcium-rich foods lowered BTM over the course of a day with several training sessions.

CONCLUSIONS

Preexercise intake of a calcium-rich meal before training sessions undertaken within the same day had a cumulative and prolonged effect on the stabilization of blood iCa during exercise. In turn, this reduced the postexercise PTH response, potentially attenuating the increase in markers of bone resorption. Such practical strategies may be integrated into the athlete's overall sports nutrition plan, with the potential to safeguard long-term bone health and reduce the risk of bone stress injuries.

Load carriage aerobic exercise stimulates a transient rise in biochemical markers of bone formation and resorption

Exercise can be both anabolic and catabolic for bone tissue. The temporal response of both bone formation and resorption following an acute bout of exercise is not well described. We assayed biochemical markers of bone and calcium metabolism for up to 3 days after military-relevant exercise. In randomized order, male (n = 18) and female (n = 2) Soldiers (means ± SD; 21.2 ± 4.1 years) performed a 60-min bout of load carriage (30% body mass; 22.4 ± 3.7 kg) treadmill exercise (EXER) or a resting control trial (REST). Blood samples were collected following provision of a standardized breakfast before (PRE), after (POST) exercise/rest, 1 h, 2 h, and 4 h into recovery. Fasted samples were also collected at 0630 on EXER and REST and for the next three mornings after EXER. Parathyroid hormone and phosphorus were elevated (208% and 128% of PRE, respectively, P < 0.05), and ionized calcium reduced (88% of PRE, P < 0.05) after EXER. N-terminal propeptide of type 1 collagen was elevated at POST (111% of PRE, P < 0.05), and the resorption marker, C-terminal propeptide of type 1 collagen was elevated at 1 h (153% of PRE, P < 0.05). Osteocalcin was higher than PRE at 1 through 4 h post EXER (119%-120% of PRE, P < 0.05). Sclerostin and Dickkopf-related protein-1 were elevated only at POST (132% and 121% of PRE, respectively, P < 0.05) during EXER. Trivial changes in biomarkers during successive recovery days were observed. These results suggest that 60 min of load carriage exercise elicits transient increases in bone formation and resorption that return to pre-exercise concentrations within 24 h post-exercise.NEW & NOTEWORTHY In this study, we demonstrated evidence for increases in both bone formation and resorption in the first 4 h after a bout of load carriage exercise. However, these changes largely disappear by 24 h after exercise. Acute formation and resorption of bone following exercise may reflect distinct physiological mechanoadaptive responses. Future work is needed to identify ways to promote acute post-exercise bone formation and minimize post-exercise resorption to optimize bone adaptation to exercise.

Is the Use of Bisphosphonates Putting Horses at Risk? An Osteoclast Perspective

Simple Summary

Bisphosphonates are a group of drugs that intervene in the bone resorption process, producing cellular death of osteoclasts. These drugs are used for skeletal conditions, such as osteoporosis in humans, and are available for veterinary medical use. Clodronate and tiludronate are bisphosphonates approved for the treatment of navicular syndrome in horses over four years old. However, these drugs are sometimes used in juvenile animals under exercise, where osteoclast activity is higher. Bisphosphonate use in juvenile and/or exercising animals could have adverse effects, including maladaptation to exercise or accumulation of microdamage. Furthermore, bisphosphonates can be bound to the skeleton for several years, resulting in a prolonged effect with no pharmaceutical reversal available. This review presents an overview of osteoclast function and a review of bisphosphonate characteristics, mechanisms of action, and side effects in order to contextualize the potential for adverse/side effects in young or exercising animals.

Abstract

Osteoclasts are unique and vital bone cells involved in bone turnover. These cells are active throughout the individual’s life and play an intricate role in growth and remodeling. However, extra-label bisphosphonate use may impair osteoclast function, which could result in skeletal microdamage and impaired healing without commonly associated pain, affecting bone remodeling, fracture healing, and growth. These effects could be heightened when administered to growing and exercising animals. Bisphosphonates (BPs) are unevenly distributed in the skeleton; blood supply and bone turnover rate determine BPs uptake in bone. Currently, there is a critical gap in scientific knowledge surrounding the biological impacts of BP use in exercising animals under two years old. This may have significant welfare ramifications for growing and exercising equids. Therefore, future research should investigate the effects of these drugs on skeletally immature horses.

Sex differences in tibial adaptations to arduous training: An observational cohort study

Military training increases tibial density and size, but it is unknown if men and women adapt similarly to the same arduous training. Seventy-seven men and 57 women not using hormonal contraceptives completed this study. Tibial volumetric bone mineral density (vBMD) and geometry were measured by peripheral quantitative computed tomography (4%, 14%, 38%, and 66% sites) at the start (week 1) and end (week 14) of British Army basic training. Training increased trabecular vBMD (4% site in men; 4% and 14% sites in women), cortical vBMD (38% site), total area (14% and 38% sites), trabecular area (14% site), cortical area and thickness (14%, 38%, and 66% sites), periosteal perimeter (14%, 38%, and 66% sites), and all indices of estimated strength (14%, 38%, and 66% sites); and, decreased endosteal perimeter (66% site) in men and women (all p ≤ 0.045). The increase in trabecular vBMD (4% and 14% sites) was greater in women and the increases in cortical area and strength (38% site) were greater in men (sex × time interactions, all p ≤ 0.047). P1NP increased and βCTX and sclerostin decreased during training in men and women, consistent with adaptive bone formation. PTH decreased in men but increased in women. Arduous weight-bearing activity increased the density and size of the tibia after 14 weeks. Women experienced similar tibial adaptations as men, however, a greater increase in trabecular vBMD in women compared with men could be due to higher loading at this skeletal site in women, whereas the small increase in cortical area could be due to inhibitory effects of oestradiol.

Low energy availability surrogates associated with lower bone mineral density and bone stress injury site

BACKGROUND

Exercise is an osteogenic stimulus that should increase bone mineral density (BMD) and protect against injury. However, some female athletes have lower BMD and increased bone stress injury (BSI) risk. Impaired bone health seen in athletes may be explained by low energy availability as described by concepts of Relative Energy Deficiency in Sport (RED-S) and Female Athlete Triad (Triad).

OBJECTIVE

To elucidate the relationship between RED-S/Triad risk factors and BSI to high-risk (femoral neck, sacrum) and low-risk (other) bones.

DESIGN

Cross-sectional survey and retrospective chart review.

SETTING

Tertiary care academic center.

PATIENTS

Female athletes aged 15-30 years participating in ≥4 h/week of exercise presenting to sports medicine/orthopedics clinic who had a self-reported BSI and available dual-energy x-ray absorptiometry (DXA) measurement of BMD.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASUREMENTS

Location of BSI.

RESULTS

In 127 athletes, high-risk BSI was associated with surrogates of low energy availability (p = .032) and having a DXA Z-score < -1 (p = .035) but not a current/past history of menstrual dysfunction (p = .348). Accumulating RED-S/Triad risk factors increase the odds of incurring a high-risk BSI (p = .048).

CONCLUSIONS

Adolescent/young female athletes who sustain BSI at high-risk sites (femoral neck, sacrum) may have underlying risk factors (eg, low energy availability, poor overall bone health) that should prompt further workup and referral to optimize health in these athletes.

Acute Effects of Milk vs. Carbohydrate on Bone Turnover Biomarkers Following Loading Exercise in Young Adult Females

Dairy products and impact exercise have previously been identified to be independently beneficial for bone mineral properties, however, it is unknown how the combination of these two osteogenic interventions may alter acute bone turnover. Using a randomized crossover design, we compared the acute effects of consuming milk vs. an isoenergetic carbohydrate control beverage on bone biomarkers following loading exercise. Thirteen healthy female participants (Age = 20.3 ± 2.3y; BMI = 21.0 ± 1.1 kg/m2) consumed either 550 mL of 0% skim white milk (MILK) or 52.7 g of maltodextrin in 550 mL of water (CHO), both 5 min and 1 h following completion of a combined plyometric (198 impacts) and resistance exercise (3-4 sets/exercise, 8-12 reps/set, ∼75% 1-RM) bout. Venous blood samples were obtained pre-exercise, and 15 min, 75 min, 24 h and 48 h post-exercise to assess serum concentrations of bone resorption biomarkers, specifically carboxyl-terminal crosslinking telopeptide of type I collagen (CTX), receptor activator nuclear factor kappa-β ligand (RANKL), and sclerostin (SOST), as well as bone formation biomarkers, specifically osteoprotegerin (OPG) and osteocalcin (OC). When absolute biomarker concentrations were examined, there were no interaction or group effects for any biomarker, however, there were main time effects (p < 0.05) for RANKL, SOST, and OC, which were lower, and the OPG: OPG/RANKL ratio, which was higher at 75 min post-exercise compared with baseline in both conditions. In addition to assessing absolute biomarker concentrations at specific timepoints, we also evaluated the relative (% change) cumulative post-exercise response (75 min to 48 h) using an area under the curve (AUC) analysis. This analysis showed that the relative post-exercise CTX response was significantly lower in the MILK compared to the CHO condition (p = 0.03), with no differences observed in the other biomarkers. These results show that while milk does not appear to alter absolute concentrations of bone biomarkers compared to CHO, it may attenuate relative post-exercise bone resorption (i.e., blunt the usual catabolic response to exercise).

Bone Turnover Alterations after Completing a Multistage Ultra-Trail: A Case Study

A series of case studies aimed to assess bone and stress fractures in a 768-km ultra-trail race for 11 days. Four nonprofessional male athletes completed the event without diagnosing any stress fracture. Bone turnover markers (osteocalcin (OC), serum C-terminal cross-linking telopeptide of type I collagen (CTX), bone-specific alkaline phosphatase (BALP), and serum turnover calcium (Ca²⁺)) were assessed before (pre) and after the race (post) and on days two and nine during the recovery period (rec2 and rec9), respectively. Results showed: post-pre-OC = −45.78%, BALP = −61.74%, CTX = +37.28% and Ca²⁺ = −3.60%. At rec2 and rec9, the four parameters did not return to their pre-run levels: OC, −48.31%; BALP, −61.66%; CTX, +11.93% and Ca²⁺, −3.38%; and OC = −25.12%, BALP = −54.65%, CTX = +93.41% and Ca²⁺ = +3.15%), respectively. Our results indicated that the ultra-trail race induced several changes in bone turnover markers, uncoupling of bone metabolism, increased bone resorption: OC and BALP and suppressed bone formation: CTX and Ca²⁺. Bone turnover markers can help determine the response of bone to extreme effort and might also help predict the risk of stress fractures.

Underlying Causes and Co-existence of Malnutrition and Infections: An Exceedingly Common Death Risk in Cancer

In nutrition science, malnutrition is a state of imbalance between intake and the needs of the organism, leading to metabolic changes, impaired physiological functions, and weight loss. Regardless of the countless efforts being taken and researched for years, the burden of malnutrition is still alarming and considered a significant agent of mortality across the globe. Around 45% of 12 million children deaths (0–5 years old) annually are due to malnutrition, mostly from developing countries. Malnutrition develops associations with other infections and leads to substantial clinical outcomes, such as mortality, more visits to hospitals, poor quality of life and physical frailty, and socioeconomic issues. Here, in this review, we intend to provide an overview of the current burden, underlying risk factors, and co-existence of malnutrition and other infections, such as cancer. Following the rising concern of the vicious interplay of malnutrition and other medical illnesses, we believed that this narrative review would highlight the need to re-make and re-define the future strategies by giving comprehensive and sustainable programs to alleviate poverty and combat the rampant infectious diseases and those nutrition-related health problems. Furthermore, the study also raises the concern for hospitalized malnourished cancer patients as it is crucially important to knowledge the caregiver healthcare staff for early interventions of providing nutritional support to delay or prevent the onset of malnutrition.

Said S, Ahmad Tarmizi NA, Loh SP, Lim WC, Nadarajah R, Lim HT, Mohd Zambri NH, Ho YY, Shariff Ghazali S. Non-pharmacological interventions for bone health after stroke: A systematic review

Objective

To examine the effectiveness and safety of non-pharmacological interventions to reduce bone loss among post-stroke adult patients.

Data sources

Cochrane Central Register of Controlled Trials (CENTRAL), Cochrane Database for Systematic Reviews, MEDLINE, CINAHL, ScienceDirect, Scopus, PubMed and PeDRO databases were searched from inception up to 31st August 2021.

Methods

A systematic review of randomized controlled trials, experimental studies without randomization and prospective cohort studies with concurrent control of non-pharmacological interventions for adult stroke patients compared with placebo or other stroke care. The review outcomes were bone loss, fall and fracture. The Cochrane Risk of Bias Tools were used to assess methodological quality, and Grading of Recommendations, Assessment, Development and Evaluations Framework to assess outcome quality. Synthesis Without Meta-Analysis (SWiM) was used for result synthesis.

Results

Seven studies (n = 453) were included. The methodological and outcome qualities varied from low to moderate. There were statistically significant changes between the intervention and parallel/placebo group in bone mineral density, bone mineral content, cortical thickness and bone turnover markers with specific physical and vibration therapies (p<0.05). Falls were higher in the intervention group, but no fracture was reported.

Conclusion

There was low to moderate evidence that physical and vibration therapies significantly reduced bone loss in post-stroke patients at the expense of a higher falls rate. The sample size was small, and the interventions were highly heterogeneous with different duration, intensities and frequencies. Despite osteoporosis occurring with ageing and accelerated by stroke, there were no studies on vitamin D or protein supplementation to curb the ongoing loss. Effective, high-quality non-pharmacological intervention to improve post-stroke bone health is required.

Effects of 8-week increment aerobic exercise program on bone metabolism and body composition in young non-athletes

PURPOSE

The effects of aerobic exercise on bone metabolism are still unclear. Thus, the main goal of this study was to explore if there was an effect of the short-term aerobic exercise program on the bone remodeling process and if there were sex differences in the effect of the training program on bone metabolism.

METHODS

Twenty-one participants (men and women) aged 20-23 performed an 8-week aerobic exercise program three times per week in 1-h sessions with increases in the exercise load every 2 weeks. Bone density, bone mineral content and concentration of markers of bone metabolism: osteocalcin, C-terminal procollagen type I peptide, pyridinoline, parathyroid hormone, osteoprotegerin, and the receptor activator of nuclear kappa B ligand by ELISA were measured at the start and at the end of the study, while changes in body composition were assessed by a bioelectric impedance analysis method 6 times during the study.

RESULTS

The aerobic exercise program increased the concentration of osteocalcin (11.34 vs 14.24 ng/ml), pyridinoline (67.51 vs 73.99 nmol/l), and the receptor activator of nuclear kappa B ligand (95.122 vs 158.15 pg/ml). A statistically significant increase in bone density at neck mean (1.122 vs 1.176 g/cm³) and in bone mineral content at dual femur (33.485 vs 33.700 g) was found in women, while there was no statistically significant change at any site in men.

CONCLUSION

8 weeks of the aerobic exercise program with increment in intensity increased some of bone remodeling biomarkers and showed different effects for men and women.

A Life History Perspective on Athletes with Low Energy Availability

The energy costs of athletic training can be substantial, and deficits arising from costs unmet by adequate energy intake, leading to a state of low energy availability, may adversely impact athlete health and performance. Life history theory is a branch of evolutionary theory that recognizes that the way the body uses energy-and responds to low energy availability-is an evolved trait. Energy is a finite resource that must be distributed throughout the body to simultaneously fuel all biological processes. When energy availability is low, insufficient energy may be available to equally support all processes. As energy used for one function cannot be used for others, energetic "trade-offs" will arise. Biological processes offering the greatest immediate survival value will be protected, even if this results in energy being diverted away from others, potentially leading to their downregulation. Athletes with low energy availability provide a useful model for anthropologists investigating the biological trade-offs that occur when energy is scarce, while the broader conceptual framework provided by life history theory may be useful to sport and exercise researchers who investigate the influence of low energy availability on athlete health and performance. The goals of this review are: (1) to describe the core tenets of life history theory; (2) consider trade-offs that might occur in athletes with low energy availability in the context of four broad biological areas: reproduction, somatic maintenance, growth, and immunity; and (3) use this evolutionary perspective to consider potential directions for future research.

Sclerostin and bone turnover markers response to cycling and running at the same moderate-to-vigorous exercise intensity in healthy men

BACKGROUND

Recreational cycling is a popular activity which stimulates and improves cardiovascular fitness. The corresponding benefits for bone are unclear.

PURPOSE

This study examined the effect of running (high-impact) vs. cycling (low-impact), at the same moderate-to-vigorous exercise intensity, on markers of bone formation (N-terminal propeptide of type I collagen, PINP) and bone resorption (C-telopeptide of type I collagen, CTX-1), a non-collagenous bone remodeling marker (osteocalcin), as well as bone-modulating factors, including parathyroid hormone (PTH), irisin (myokine) and sclerostin (osteokine).

METHODS

Thirteen healthy men (23.7 ± 1.0 y) performed two progressive exercise tests to exhaustion (peak VO₂) on a cycle ergometer (CE) and on a treadmill (TM). On subsequent separate days, in randomized order, participants performed 30-min continuous running or cycling at 70% heart rate reserve (HRR). Blood was drawn before, immediately post- and 1 h into recovery.

RESULTS

PTH transiently increased (CE, 51.7%; TM, 50.6%) immediately after exercise in both exercise modes. Sclerostin levels increased following running only (27.7%). Irisin increased following both running and cycling. In both exercise modes, CTX-1 decreased immediately after exercise, with no significant change in PINP and osteocalcin.

CONCLUSION

At the same moderate-to-vigorous exercise intensity, running appears to result in a greater transient sclerostin response compared with cycling, while the responses of bone markers, PTH and irisin are similar. The longer-term implications of this differential bone response need to be further examined.

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.

Response of Bone Metabolism Markers to Ice Swimming in Regular Practitioners

Objective: Both exercise and cold exposure cause physiological stress and they often occur in combination. However, the effects of exercise during severe cold on variation in bone metabolism in humans have remained elusive. The aim of this study was to investigate the variations in circulating bone metabolism markers after ice swimming (IS).

Methods: Eighty-seven women and men aged 42–84 years old were recruited to perform regular IS activities. Serum parathyroid hormone (PTH), total calcium (Ca²⁺), total phosphorus (Pi), total magnesium (Mg²⁺), N-terminal osteocalcin (N-MID), total propeptide of procollagen 1 (TPINP), and C-terminal telopeptide of type 1 collagen (β-CTX) were measured 30 min before and 30 min after IS. Bone mineral content (BMC) and bone mineral density (BMD) were assessed at lumbar spine 1–4 (L1–L4) and femoral neck (FN). The IS habits were obtained from questionnaires and the 10-year probability of osteoporotic fracture was calculated using the FRAX^® tool with and without a BMD value of the FN.

Results: There were significant increases in PTH (median, 40.120–51.540 pg/mL), Ca²⁺ (median, 2.330–2.400 mmol/L), and Pi (median, 1.100–1.340 mmol/L) and significant decreases in TPINP (median, 38.190–36.610 ng/mL) and β-CTX (median, 0.185–0.171 ng/mL), while there was a trend for increased serum Mg²⁺ (P = 0.058) but no significant change in N-MID (P = 0.933) after IS in all subjects. The increases in the proportions of cases of hyperparathyroidemia, hypercalcemia, and hyperphosphatemia in those performing IS were statistically significant. The baseline levels and the changes of bone metabolism markers had associations with osteoporosis and bone status, but these may be age and sex dependent. Finally, there were significant correlations among the bone metabolism markers.

Conclusion: IS caused significant alterations in bone metabolic markers, specifically, increases in PTH, Ca²⁺ and Pi should raise concerns about potential cardiovascular health risks in severe cold exercise. Additionally, a divergence between PTH elevation and a decline in bone turnover, which shown a special change of bone metabolism after IS and may suggest potential therapeutic implications of cold exercise in PTH and bone metabolic disorders.

Three-Dimensional Co-Culture System of Human Osteoblasts and Osteoclast Precursors from Osteoporotic Patients as an Innovative Model to Study the Role of Nutrients: Focus on Vitamin K2

Several natural compounds, such as vitamin K2, have been highlighted for their positive effects on bone metabolism. It has been proposed that skeletal disorders, such as osteoporosis, may benefit from vitamin K2-based therapies or its regular intake. However, further studies are needed to better clarify the effects of vitamin K2 in bone disorders. To this aim, we developed in vitro a three-dimensional (3D) cell culture system one step closer to the bone microenvironment based on co-culturing osteoblasts and osteoclasts precursors obtained from bone specimens and peripheral blood of the same osteoporotic patient, respectively. Such a 3-D co-culture system was more informative than the traditional 2-D cell cultures when responsiveness to vitamin K2 was analyzed, paving the way for data interpretation on single patients. Following this approach, the anabolic effects of vitamin K2 on the osteoblast counterpart were found to be correlated with bone turnover markers measured in osteoporotic patients’ sera. Overall, our data suggest that co-cultured osteoblasts and osteoclast precursors from the same osteoporotic patient may be suitable to generate an in vitro 3-D experimental model that potentially reflects the individual’s bone metabolism and may be useful to predict personal responsiveness to nutraceutical or drug molecules designed to positively affect bone health.

Sclerostin and bone remodeling biomarkers responses to whole-body cryotherapy (- 110 °C) in healthy young men with different physical fitness levels

We investigated the effects of single and repeated exposures to whole-body cryotherapy on biomarkers of bone remodeling and osteo-immune crosstalk: sclerostin, osteocalcin (OC), C-terminal cross-linked telopeptide of type I collagen (CTx-I), osteoprotegerin (OPG) and free soluble receptor activator for nuclear factor κ B ligand (sRANKL). The study included 22 healthy males, grouped in high physical fitness level (HPhL) and low physical fitness level (LPhL), all undergone 10 consecutive sessions in a cryogenic chamber (- 110 °C). We observed a significant time-effect on sclerostin (p < 0.05), OC (p < 0.01), CTx-I (p < 0.001), OC/CTx-I (p < 0.05), and significant differences in sRANKL between the groups (p < 0.05) after the 1st cryostimulation; a significant time-effect on OC (p < 0.001) and OC/CTx-I (p < 0.001) after the 10th cryostimulation, and a significant time-effect on CTx-I (p < 0.001) and OC/CTx-I (p < 0.01) after 10 sessions of WBC. In conclusion, in young men, the first exposure to extreme cold induced significant changes in serum sclerostin. The changes in sRANKL, between groups, suggest that fitness level may modify the body's response to cold. The effects of the first stimulus and the whole session are not identical, probably due to the physiological development of habituation to cold.

One year of Football Fitness improves L1-L4 BMD, postural balance, and muscle strength in women treated for breast cancer

PURPOSE

To examine efficacy of 12 months Football Fitness offered twice per week on bone mineral density (BMD), bone turnover markers (BTM), postural balance, muscle strength, and body composition in women treated for early-stage breast cancer (BC).

METHODS

Women treated for early-stage BC were randomized to Football Fitness (FFG, n = 46) or control (CON, n = 22) in a 2:1 ratio for 12 months, with assessments performed at baseline, 6 months and 12 months. Outcomes were total body-, lumbar spine- and proximal femur BMD, total body lean and fat mass, leg muscle strength, postural balance, and plasma amino-terminal propeptide of type 1 procollagen (P1NP), osteocalcin, and C-terminal telopeptide of type 1 collagen (CTX). Intention-to-treat (ITT) analyses and per-protocol analyses (≥50% attendance in FFG) were performed using linear mixed models.

RESULTS

Participants in FFG completing the 12-month intervention (n = 33) attended 0.8 (SD = 0.4) sessions per week. Intention to treat analysis of mean changes over 12 months showed significant differences (p<.05) in L1-L4 BMD (0.029 g/cm2 , 95%CI: 0.001 to 0.057), leg press strength (7.2 kg, 95%CI: 0.1 to 14.3), and postural balance (-4.3 n need of support, 95%CI: -8.0 to -0.7) favoring FFG compared to CON. In the per-protocol analyses, L1-L4 and trochanter major BMD were improved (p = .012 and .030, respectively) in FFG compared with CON. No differences were observed between groups in BTMs in the ITT or per protocol analyses.

CONCLUSION

One year of Football Fitness training may improve L1-L4 BMD, leg muscle strength, and postural balance in women treated for early-stage breast cancer.

A collagen extraction and deuterium oxide stable isotope tracer method for the quantification of bone collagen synthesis rates in vivo

The development of safe and practical strategies to prevent weakening of bone tissue is vital, yet attempts to achieve this have been hindered by a lack of understanding of the short-term (days-weeks) physiology of bone collagen turnover. To address this, we have developed a method to quantify bone collagen synthesis in vivo, using deuterium oxide (D₂ O) tracer incorporation techniques combined with gas chromatography pyrolysis isotope-ratio mass spectrometry (GC-pyrolysis-IRMS). Forty-six male and female rats from a selectively bred model ingested D₂ O for 3 weeks. Femur diaphyses (FEM), tibia proximal (T-PRO), and distal (T-DIS) epiphyses-metaphyses and tibia mid-shaft diaphyses (T-MID) were obtained from all rats after necropsy. After demineralisation, collagen proteins were isolated and hydrolysed and collagen fractional synthetic rates (FSRs) determined by incorporation of deuterium into protein-bound alanine via GC-pyrolysis-IRMS. The collagen FSR for the FEM (0.131 ± 0.078%/day; 95% CI [0.106-0.156]) was greater than the FSR at T-MID (0.055 ± 0.049%/day; 95% CI [0.040-0.070]; p < 0.001). The T-PRO site had the highest FSR (0.203 ± 0.123%/day; 95% CI [0.166-0.241]) and T-DIS the lowest (0.027 ± 0.015%/day; 95% CI [0.022-0.031]). The three tibial sites exhibited different FSRs (p < 0.001). Herein, we have developed a sensitive method to quantify in vivo bone collagen synthesis and identified site-specific rates of synthesis, which could be applicable to studies of human bone collagen turnover.

Effects of Low Energy Availability on Bone Health in Endurance Athletes and High-Impact Exercise as A Potential Countermeasure: A Narrative Review

Endurance athletes expend large amounts of energy in prolonged high-intensity exercise and, due to the weight-sensitive nature of most endurance sports, often practice periods of dietary restriction. The Female Athlete Triad and Relative Energy Deficiency in Sport models consider endurance athletes at high-risk for suffering from low energy availability and associated health complications, including an increased chance of bone stress injury. Several studies have examined the effects of low energy availability on various parameters of bone structure and markers of bone (re)modelling; however, there are differences in findings and research methods and critical summaries are lacking. It is difficult for athletes to reduce energy expenditure or increase energy intake (to restore energy availability) in an environment where performance is a priority. Development of an alternative tool to help protect bone health would be beneficial. High-impact exercise can be highly osteogenic and energy efficient; however, at present, it is rarely utilized to promote bone health in endurance athletes. Therefore, with a view to reducing the prevalence of bone stress injury, the objectives of this review are to evaluate the effects of low energy availability on bone health in endurance athletes and explore whether a high-impact exercise intervention may help to prevent those effects from occurring.

Bone Metabolism, Bone Mineral Content, and Density in Elite Late Teen Female Sprinters

With intensive training, bone injuries are a major concern for athletes. To assess bone condition, we often measure bone turnover markers, bone mineral content and density; however, in junior athletes, it is not easy to distinguish changes caused by bone injuries from those caused by growth, because the metabolism is increased in both cases. Moreover, although some studies have examined female endurance athletes, knowledge regarding changes in static and dynamic bone conditions in late teen athletes is limited. In this study, we measured the bone mineral content and density, as well as bone turnover markers, in 40 elite female sprinters in their late teens. Whole body mode dual-energy X-ray absorptiometry was performed to measure bone mineral content and density. Blood samples were collected to determine bone resorption and formation markers at the end of track season in 2016 and during the same period of the following year. Body weight and bone mineral content significantly increased, and tartrate-resistant acid phosphatase type 5b, bone-type alkaline phosphatase, and osteocalcin significantly decreased after a year. Furthermore, the rate of change in bone mineral content was higher in younger athletes, indicating that bone growth approaches completion in the late teen years and that bone metabolism accordingly decreases.

Low energy availability in female athletes: From the lab to the field

Decades of laboratory research have shown impairments to several body systems after only 4-5 days of strictly controlled consistent low energy availability (LEA); where energy availability (EA) = Energy Intake (EI) - Exercise Energy Expenditure (EEE)/Fat-Free Mass. Meanwhile, cross-sectional reports exist on the interrelatedness of LEA, menstrual dysfunction and impaired bone health in females (the Female Athlete Triad). These findings have demonstrated that LEA is the key underpinning factor behind a broader set of health and performance outcomes, recently termed as Relative Energy Deficiency in Sport (RED-S). There is utmost importance of early screening and diagnosis of RED-S to avoid the development of severe negative health and performance outcomes. However, a significant gap exists between short-term laboratory studies and cross-sectional reports, or clinically field-based situations, of long-term/chronic LEA and no definitive, validated diagnostic tests for RED-S exist. This review aims to highlight methodological challenges related to the assessment of the components of EA equation in the field (e.g. challenges with EI and EEE measures). Due to the uncertainty of these parameters, we propose the use of more chronic "objective" markers of LEA (i.e. blood markers). However, we note that direct extrapolations of laboratory-based outcomes into the field are likely to be problematic due to potentially poor ecological validity and the extreme variability in most athlete's daily EI and EEE. Therefore, we provide a critical appraisal of the scientific literature, highlighting research gaps, and a potential set of leading objective RED-S markers while working in the field.HIGHILIGHTS Direct application of short-term laboratory-based findings in the field is problematic.Calculation of energy availability (EA) in the field is methodologically challenging and prone to errors.The use of several biomarkers may allow the detection of early exposure to low EA in the female athlete.

The influence of acute exercise on bone biomarkers: protocol for a systematic review with meta-analysis

BACKGROUND

Bone is a plastic tissue that is responsive to its physical environment. As a result, exercise interventions represent a potential means to influence the bone. However, little is currently known about how various exercise and participant characteristics interact to influence bone metabolism. Acute, controlled, interventions provide an in vivo model through which the acute bone response to exercise can be investigated, typically by monitoring circulating bone biomarkers. Currently, substantial heterogeneity in factors such as study design, quality, exercise, and participant characteristics render it difficult to synthesize and evaluate the available evidence. Using a systematic review and meta-analytic approach, the aim of this investigation is to quantify the effect of an acute exercise bout on circulating bone biomarkers as well as examine the potential factors that may moderate this response, e.g., variation in participant, exercise, and sampling characteristics.

METHODS

This protocol was designed in accordance with the PRISMA-P guidelines. Seven databases (MEDLINE, Embase, Sport Discus, Cochrane CENTRAL, PEDro, LILACS, and Ibec) will be systematically searched and supplemented by a secondary screening of the reference lists of all included articles. The PICOS (Population, Intervention, Comparator, Outcomes and Study Design) approach was used to guide the determination of the eligibility criteria. Participants of any age, sex, training, or health status will be considered for inclusion. We will select studies that have measured the bone biomarker response before and after an acute exercise session. All biomarkers considered to represent the bone metabolism will be considered for inclusion, and sensitivity analyses will be conducted using reference biomarkers for the measurement of bone resorption and formation (namely β-CTX-1 and P1NP). Multi-level, meta-regression models within a Bayesian framework will be used to explore the main effect of acute exercise on bone biomarkers as well as potential moderating factors. The risk of bias for each individual study will be evaluated using a modified version of the Downs and Black checklist while certainty in resultant outcomes will be assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

DISCUSSION

A better understanding of the bone metabolic response to an acute bout of exercise has the potential to advance our understanding of the mechanisms through which this stimulus impacts bone metabolism, including factors that may moderate this response. Additionally, we will identify current gaps in the evidence base and provide recommendations to inform future research.

SYSTEMATIC REVIEW REGISTRATION

This protocol was prospectively registered in the Open Science Framework Registry ( https://osf.io/6f8dz ).