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      The Effects of a Calcium-Rich Pre-Exercise Meal on Biomarkers of Calcium Homeostasis in Competitive Female Cyclists: A Randomised Crossover Trial

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          Abstract

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

          Purpose

          To examine whether a calcium-rich pre-exercise meal attenuates exercise-induced perturbations of bone calcium homeostasis caused by maintenance of sweat calcium losses.

          Methods

          Using a randomized, counterbalanced crossover design, 32 well-trained female cyclists completed two 90 min cycling trials separated by 1 day. Exercise trials were preceded 2 hours by either a calcium-rich (1352 ± 53 mg calcium) dairy based meal (CAL) or a control meal (CON; 46 ± 7 mg calcium). Blood was sampled pre-trial; pre-exercise; and immediately, 40 min, 100 min and 190 min post-exercise. Blood was analysed for ionized calcium and biomarkers of bone resorption (Cross Linked C-Telopeptide of Type I Collagen (CTX-I), Cross Linked C-Telopeptide of Type II Collagen (CTX-II), Parathyroid Hormone (PTH), and bone formation (Procollagen I N-Terminal Propeptide (PINP)) using the established enzyme-linked immunosorbent assay technique.

          Results

          PTH and CTX-I increased from pre-exercise to post-exercise in both conditions but was attenuated in CAL (p < 0.001). PTH was 1.55 [1.20, 2.01] times lower in CAL immediately post-exercise and 1.45 [1.12, 1.88] times lower at 40 min post-exercise. CTX-I was 1.40 [1.15, 1.70] times lower in CAL at immediately post-exercise, 1.30 [1.07, 1.57] times lower at 40 min post-exercise and 1.22 [1.00, 1.48] times lower at 190 min post-exercise (p < 0.05). There was no significant interaction between pre-exercise meal condition and time point for CTX-II (p = 0.732) or PINP (p = 0.819).

          Conclusion

          This study showed that a calcium-rich pre-exercise breakfast meal containing ~1350 mg of calcium consumed ~90 min before a prolonged and high intensity bout of stationary cycling attenuates the exercise induced rise in markers of bone resorption – PTH and CTX-I.

          Trial Registration

          Australian New Zealand Clinical Trials Registry ACTRN12614000675628

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          Most cited references24

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          American College of Sports Medicine position stand. Exercise and fluid replacement.

          Michael N Sawka, Louise M Burke, E Randy Eichner … (2007)
          This Position Stand provides guidance on fluid replacement to sustain appropriate hydration of individuals performing physical activity. The goal of prehydrating is to start the activity euhydrated and with normal plasma electrolyte levels. Prehydrating with beverages, in addition to normal meals and fluid intake, should be initiated when needed at least several hours before the activity to enable fluid absorption and allow urine output to return to normal levels. The goal of drinking during exercise is to prevent excessive (>2% body weight loss from water deficit) dehydration and excessive changes in electrolyte balance to avert compromised performance. Because there is considerable variability in sweating rates and sweat electrolyte content between individuals, customized fluid replacement programs are recommended. Individual sweat rates can be estimated by measuring body weight before and after exercise. During exercise, consuming beverages containing electrolytes and carbohydrates can provide benefits over water alone under certain circumstances. After exercise, the goal is to replace any fluid electrolyte deficit. The speed with which rehydration is needed and the magnitude of fluid electrolyte deficits will determine if an aggressive replacement program is merited.
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            Timing and distribution of protein ingestion during prolonged recovery from resistance exercise alters myofibrillar protein synthesis.

            José Areta, Louise M Burke, Megan Ross … (2013)
            Quantity and timing of protein ingestion are major factors regulating myofibrillar protein synthesis (MPS). However, the effect of specific ingestion patterns on MPS throughout a 12 h period is unknown. We determined how different distributions of protein feeding during 12 h recovery after resistance exercise affects anabolic responses in skeletal muscle. Twenty-four healthy trained males were assigned to three groups (n = 8/group) and undertook a bout of resistance exercise followed by ingestion of 80 g of whey protein throughout 12 h recovery in one of the following protocols: 8 × 10 g every 1.5 h (PULSE); 4 × 20 g every 3 h (intermediate: INT); or 2 × 40 g every 6 h (BOLUS). Muscle biopsies were obtained at rest and after 1, 4, 6, 7 and 12 h post exercise. Resting and post-exercise MPS (l-[ring-(13)C6] phenylalanine), and muscle mRNA abundance and cell signalling were assessed. All ingestion protocols increased MPS above rest throughout 1-12 h recovery (88-148%, P INT>PULSE hierarchy in magnitude of phosphorylation. MuRF-1 and SLC38A2 mRNA were differentially expressed with BOLUS. In conclusion, 20 g of whey protein consumed every 3 h was superior to either PULSE or BOLUS feeding patterns for stimulating MPS throughout the day. This study provides novel information on the effect of modulating the distribution of protein intake on anabolic responses in skeletal muscle and has the potential to maximize outcomes of resistance training for attaining peak muscle mass.
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              Three rules for bone adaptation to mechanical stimuli.

              C.H. Turner (1998)
              The primary mechanical function of bones is to provide rigid levers for muscles to pull against, and to remain as light as possible to allow efficient locomotion. To accomplish this bones must adapt their shape and architecture to make efficient use of material. Bone adaptation during skeletal growth and development continuously adjusts skeletal mass and architecture to changing mechanical environments. There are three fundamental rules that govern bone adaptation: (1) It is driven by dynamic, rather than static, loading. (2) Only a short duration of mechanical loading is necessary to initiate an adaptive response. (3) Bone cells accommodate to a customary mechanical loading environment, making them less responsive to routine loading signals. From these rules, several mathematical equations can be derived that provide simple parametric models for bone adaptation.
              Article 0 comments Cited 155 times – based on 0 reviews     Review now
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                Author and article information

                Contributors
                Naoyuki Hayashi: Role: Academic Editor
                Journal
                Journal ID (nlm-ta): PLoS One
                Journal ID (iso-abbrev): PLoS ONE
                Journal ID (publisher-id): plos
                Journal ID (pmc): plosone
                Title: PLoS ONE
                Publisher: Public Library of Science (San Francisco, CA USA )
                ISSN (Electronic): 1932-6203
                Publication date (Electronic): 13 May 2015
                Publication date Collection: 2015
                Volume: 10
                Issue: 5
                Electronic Location Identifier: e0123302
                Affiliations
                [1 ]Sports Nutrition, Australian Institute of Sport, Belconnen, 2616, Australia
                [2 ]Physiology, Australian Institute of Sport, Belconnen, 2616, Australia
                [3 ]Performance Research, Australian Institute of Sport, Belconnen, 2616, Australia
                [4 ]Department of Epidemiology & Preventive Medicine, School of Public Health & Preventive Medicine, Monash University, Melbourne, 3004, Australia
                [5 ]Human Movement Studies, University of Queensland, St Lucia, 4072, Australia
                [6 ]School of Exercise Science, Australian Catholic University, Melbourne, 3065, Australia
                Tokyo Institute of Technology, JAPAN
                Author notes

                Competing Interests: The authors have declared that no competing interests exist.

                Conceived and designed the experiments: ECH MLR EJK AEW FMC BHW LMB. Performed the experiments: ECH MLR LEC AN BHW. Analyzed the data: ECH EJK LMB. Contributed reagents/materials/analysis tools: EJK BHW. Wrote the paper: ECH MLR DGJ LMB.

                Article
                Publisher ID: PONE-D-14-24518
                DOI: 10.1371/journal.pone.0123302
                PMC ID: 4430171
                PubMed ID: 25970439
                SO-VID: 0255eeac-4b70-4be1-829c-a8287ade8486
                Copyright statement: Copyright @ 2015
                License:

                This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

                History
                Date received : 6 July 2014
                Date accepted : 26 February 2015
                Page count
                Figures: 3, Tables: 3, Pages: 16
                Funding
                This project was funded by Dairy Australia ( www.dairyaustralia.com.au). Funding was received by LMB as a representative of the Australian Institute of Sport. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. The Australian Institute of Sport, Applied Research Centre supported this project through the provision of staff, facilities and equipment. Cycling Australia supported this project by providing coaching staff to assist with the logistics of the project.
                Categories
                Subject: Research Article
                Custom metadata
                Data Availability All relevant data are within the paper and its Supporting Information files.

                ScienceOpen disciplines: Uncategorized
                Data availability:
                ScienceOpen disciplines: Uncategorized

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