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Cycling Duration and Bone Markers in in Active Young Adults


Study First Submitted Date 2020-05-05
Study First Posted Date 2020-05-08
Last Update Posted Date 2023-06-06
Start Month Year April 20, 2024
Primary Completion Month Year August 30, 2025
Verification Month Year June 2023
Verification Date 2023-06-30
Last Update Posted Date 2023-06-06

Detailed Descriptions

Sequence: 20758824
Description Introduction: Exercise has been shown to positively benefit bone health. It’s well documented that an acute bout of weight bearing, high load and dynamic strain on the skeleton mobilizes markers of bone formation in normal weight males and females. Acute bouts of low-impact high intensity exercise such as cycling, have also been investigated for their effects on bone formation and resorption, showing an overall anabolic effect (Mezil et al. 2015). One study exists investigating an acute two-hour bout of moderate intensity cycling, which showed increases in parathyroid hormone, associated with bone metabolism, although the effects of these transient hormonal changes on bone remain unknown (Barry & Kohrt, 2007). Minimal research has investigated the effects of acute bouts of moderate intensity continuous cycling (70% of VO2 max) on bone metabolism. In contrast to these acute controlled studies, at least two studies have reported that athletes who regularly participate in non-weight bearing sports such as cycling present with higher rates of osteopenia in the lumbar spine and hip region (Rector et al. 2008; Sherk et al. 2013). Another study investigated the bone status of adolescent male cyclists, over 17 and under 17 years of age, compared to healthy age matched controls. Cyclists had lower BMD at the legs, pelvis, and total hip. In cyclists over 17, reported BMD was 8.9% to 24.5% lower for the whole body, pelvis, femoral hip and legs, suggesting cycling performed during adolescent years may negatively affects bone health and one’s ability to reach peak bone mass during this critical time (Olmedillas et al. 2011). However, a small study investigating 5 male elite racers during a 6-day road cycling stage race, while meeting energy needs, showed an increase markers of bone formation and a decrease in markers of bone resorption (Hinton et al. 2010). Thus, the evidence provided above appears contradictory. On the one hand, an acute bout of high intensity cycling has an osteogenic effect on bone, while longer-term studies or observational data, which allow for the time required to see changes in BMD, appear to show that road cycling can also have an osteocatabolic effect on bone (Olmedillas et al. 2012). This contradiction raises interesting questions about the impacts of larger loads of cycling, energy intakes, as well as the impacts of longer durations of cycling on bone health. There appear to be conditions related to the sport of road cycling, not specific to the mechanics of cycling itself, that can predispose an athlete to low BMD over time. These conditions remain unclear. Possible factors contributing to the lower BMD found in cyclists include low energy availability and its associated hormonal and nutritional implications, carbohydrate availability, the omission of weight bearing loads due to long hours spent performing non-weight cycling, weight loss, as well as excess calcium losses through sweat and urine. Recent studies have also provided evidence of the importance of consuming carbohydrates in attenuating markers bone resorption and supporting bone health during exercise (Heikura et al. 2019). Of interest, is the fact that gymnasts, athletes who also often train under conditions of low energy availability, appear to gain a protective effect from their high impact sport, that overrides the bone resorption typically associated with calorie deficits. The high mechanical forces in this sport have large osteogenic effects, maintaining BMD, unlike what has been observed in cyclists (Robinson et al. 1995). This makes one question if it is the non-weight bearing nature of cycling, certain conditions surrounding cycling or something inherent to the mechanical aspects of cycling itself, that have a seemingly negative impact on bone? To date, researchers have investigated the effects of an acute bout of high intensity cycling on markers of bone formation and resorption, as well as moderate intensity cycling and its effects on bone. Field studies have been executed where energy needs have been met and where energy deficiency was present. There is a gap in the research as far as the impact of duration of moderate intensity cycling on bone, in an energy replete state, in a controlled setting. Filling this gap through a systematic approach would help to better understand if and how duration impacts the metabolic bone response. There are a variety of methods to measure the bone’s response to acute mechanical loading. Since changes in BMD are not immediate, and only occur over longer time periods, this measurement is not appropriate to use to investigate changes in bone metabolism after one acute bout of exercise. After an acute bout of exercise, it is common to measure circulating bone turnover markers. These markers are products of bone formation or resorption. There are a variety of bone turnover markers, however some of the more commonly used are procollagen I intact N-terminal (PINP) and C-terminal crosslinking telopeptides of type I collagen (CTX), which are recognized by the International Osteoporosis Foundation (IOF) and are products of osteoblastic or osteoclastic cell activation, respectively. More recently, bone metabolism has been investigated through measures of the glycoprotein sclerostin, an inhibitor of the Wnt pathway, which leads to decreased bone formation. The Wnt/β-catenin signalling process has influence on the mobilization of OPG (Osteoprotegerin). OPG binds to receptor activator of nuclear factor kappa-β ligand (RANKL), preventing RANKL from binding to RANK (an osteoclast cell surface receptor), acting as a decoy receptor. RANKL binding to RANK would otherwise increase bone resorption. Therefore, the two pathways, Wnt-B-catenin and OPG/RANKL have a relationship that can help us to better understand the processes of bone resorption and formation. Purpose: This study aims to investigate differences in markers of bone metabolism (CTX, PINP) and osteokines (sclerostin, OPG and RANKL) between three moderate intensity cycling trials of different duration (30, 60 and 120 min) in an energy and carbohydrate replete state. The question the investigators aim to answer is whether there is a threshold of time where continued stimulus from moderate strain on the bone fails to elicit an additional metabolic response in bone or even becomes osteocatabolic, when athletes are in an energy replete state. Additional biochemical responses to the exercise will also be examined including inflammatory markers, glucose, anabolic/hormonal markers and oxidative stress. Methods: Fifteen 20-30-year-old active male participants (sample size calculated based on Mezil et al. 2015) will arrive to the lab on 5 separate occasions. Visit one will include anthropometric measurements and a VO2max test. Participants will fill out a 24-hour food recall before visit one. Participants will complete one control and three continuous cycling trials (visits 2, 3, 4 and 5) on the cycle ergometer at 60-70% of their respective VO2 max based on their test from visit 1. The order of exercise sessions will be randomized. Participants will follow a balanced diet the day before visits 2 to 5, which will be based on the participants food log for the 24 hours before visit one. Adjustments will be made to participants’ food log in order to meet the macronutrient composition of 65% CHO, 25% PRO and 15% fat, to assure they arrive at the lab in an energy replete state before visits 2 to 5. Participants will also be given hydration guidelines for the 24 hours before arriving at the lab and will be asked to refrain from any vigorous activity for 24 hours before all visits to the lab. For visits 2 to 5, participants will arrive at the lab fasted for a resting blood draw followed by a standard breakfast. Thirty minutes after breakfast, a post-breakfast blood draw will be taken followed by the respective protocol of the day (control, 30-, 60- or 120-min cycling). Additional blood samples will be taken as described below. To maintain hydration during the cycling trials, participants will be provided with 500 ml (for 30 min trial) to 1L (for the 60 and 120 min trials) of water to drink at libitum. The value of these visits is to see if there is a change in bone metabolism over time between the control, and three different cycling duration protocols. Blood Samples: During the control session, a total of 7 blood samples will be taken: one upon arriving to the lab, one post-meal but before the 2-hour control session begins, and five during the control session at 30 min, 60 min, 120 min, 150 min and 180 min. During each cycling trial, a total of five (5) blood samples from each participant will be collected: one upon arriving to the lab, one post-meal but before cycling, and 3 post-cycling at 5 minutes, 30 minutes and 60 minutes after completion the cycling. The blood samples will be drawn using a catheter (IV) performed by a certified paramedic. Catheterization would be upon subject arriving to the lab, suggest base line vital signs pre and post IV placement, preferably with subject in a recumbent position for the duration of assessment and IV placement. IV placement to be preferentially placed in the left or right forearm (posterior hand if no other sites visible) with a maximum of two IV attempts per visit. IV insertion to be completed using aseptic procedures as per safety standards. IV cannula to be secured via tegaderm, hypoallergenic tape and a compliant fishnet style elastic fabric to provide added protection from displacement during heavy perspiration and movement of the subject. Cannula would be locked with a saline lock and extension for access during blood draws (see below for schedule). Each blood draw should use one initial vacutainer as a waste draw due to saline in the IV lock with the second container being a pure venous sample. Once sampling is completed, saline is reintroduced at slightly higher pressure into the saline lock to maintain patency of the cannula for the next draw. Aseptic methods used throughout each procedure. All blood samples will contain 5-10 ml of blood using serum and plasma tubes. Bone turnover markers, anabolic/hormonal markers, inflammatory markers and oxidative stress will be examined in each sample. To control for circadian rhythm, the exercise session and related blood samples will be performed at the same time of day between 9:00 am and 1:00pm. Anthropometric Measurements: Height will be assessed using a stadiometer to the nearest 0.1 cm with no shoes. Body mass (kg), relative body fat (%) and fat free mass (kg) will be measured using Bod Pod (air displacement plethysmography method). All the participants will have familiarization with Bod Pod by sitting in the chamber before the test to see if they are claustrophobic. Participants will have the choice of an investigator of the same sex to take their anthropometric measurements.


Sequence: 200420760
Name Brock University
City Saint Catharines
State Ontario
Zip L2S 3A1
Country Canada

Facility Contacts

Sequence: 28151741 Sequence: 28151742
Facility Id 200420760 Facility Id 200420760
Contact Type primary Contact Type backup
Name Panagiota Klentrou, PhD Name Bareket Falk, PhD
Email Email
Phone 905-688-5550 Phone 905-688-5550
Phone Extension 4538 Phone Extension 4979


Sequence: 52266622 Sequence: 52266623
Name Bone Loss Name Energy Supply; Deficiency
Downcase Name bone loss Downcase Name energy supply; deficiency

Id Information

Sequence: 40227967
Id Source org_study_id
Id Value REB 19-266


Sequence: 42644457
Name Canada
Removed False

Design Groups

Sequence: 55700125
Group Type Experimental
Title Participants
Description All participants will perform three moderate intensity cycling trials of different duration (30, 60 and 120 min) in an energy replete state.


Sequence: 52579342
Intervention Type Other
Name Exercise
Description Moderate intensity cycling trials of different duration (30, 60 and 120 min)


Sequence: 80004556 Sequence: 80004557 Sequence: 80004558 Sequence: 80004559 Sequence: 80004560 Sequence: 80004561 Sequence: 80004562 Sequence: 80004563
Name Bone Turnover Name biomarkers Name cycling Name energy availability Name sclerostin Name OPG/RANKL Name bone formation Name bone resorption
Downcase Name bone turnover Downcase Name biomarkers Downcase Name cycling Downcase Name energy availability Downcase Name sclerostin Downcase Name opg/rankl Downcase Name bone formation Downcase Name bone resorption

Design Outcomes

Sequence: 177731256 Sequence: 177731257 Sequence: 177731258 Sequence: 177731259 Sequence: 177731260 Sequence: 177731261 Sequence: 177731262 Sequence: 177731263 Sequence: 177731264 Sequence: 177731265 Sequence: 177731266
Outcome Type primary Outcome Type primary Outcome Type primary Outcome Type primary Outcome Type primary Outcome Type secondary Outcome Type secondary Outcome Type secondary Outcome Type secondary Outcome Type secondary Outcome Type secondary
Measure C-terminal crosslinking telopeptides of type I collagen (CTX) Measure Procollagen I intact N-terminal (PINP) Measure Sclerostin (pg/ml) Measure Osteoprotegerin (OPG) Measure Receptor activator of nuclear factor kappa-β ligand (RANKL) Measure Tumor necrosis factor alpha (TNF-a) Measure Interleukin 10 (IL-10) Measure Interleukin 6 (IL-6) Measure thiobarbituric acid reactive substances (TBARS) Measure Glucose (ng/ml) Measure Insulin growth factor one (IGF-1)
Time Frame 1 week Time Frame 1 week Time Frame 1 week Time Frame 1 week Time Frame 1 week Time Frame 1 week Time Frame 1 week Time Frame 1 week Time Frame 1 week Time Frame 1 week Time Frame 1 week
Description Bone resorption marker (ng/ml) Description Bone formation marker (ng/ml) Description Wnt related osteokine Description osteokine (pg/ml) Description osteokine (pg/ml) Description Pro-inflammatory cytokine (pg/ml) Description Anti-inflammatory cytokine (pg/ml) Description Myokine (pg/ml) Description oxidative stress marker Description metabolic marker Description metabolic marker (ng/ml)


Sequence: 48408449 Sequence: 48408450
Agency Class OTHER Agency Class OTHER
Lead Or Collaborator lead Lead Or Collaborator collaborator
Name Brock University Name Natural Sciences and Engineering Research Council, Canada

Overall Officials

Sequence: 29337052
Role Principal Investigator
Name Panagiota Klentrou
Affiliation Brock University

Central Contacts

Sequence: 12031507 Sequence: 12031508
Contact Type primary Contact Type backup
Name Panagiota Klentrou, PhD Name Anne Guzman, BSc
Phone 9056885550 Phone 9056885550
Email Email
Phone Extension 4538 Phone Extension 5826
Role Contact Role Contact

Design Group Interventions

Sequence: 68278280
Design Group Id 55700125
Intervention Id 52579342


Sequence: 30820913
Gender Male
Minimum Age 20 Years
Maximum Age 30 Years
Healthy Volunteers Accepts Healthy Volunteers
Criteria Inclusion Criteria: Caucasian males, aged 20 to 30 years, healthy (not suffering from asthma), of normal weight (BMI: 18.5 – 25 kg/m2), recreationally active (i.e., regularly exercise 3-6 times per week, including 3 times of aerobic exercise over 45 min per session). Exclusion Criteria: with no fracture over the last year, not taking any medication related to a chronic condition or bone health including food/nutritional supplements (e.g. protein, vitamin D, calcium), non-smokers, with no injuries or chronic conditions in which exercise may pose a risk (e.g., ACL or knee/hip/lower back injuries, arthritis, osteoporosis, neuromuscular diseases), currently not on a low carbohydrate or ketogenic diet.
Adult True
Child False
Older Adult False

Calculated Values

Sequence: 254107001
Number Of Facilities 1
Registered In Calendar Year 2020
Were Results Reported False
Has Us Facility False
Has Single Facility True
Minimum Age Num 20
Maximum Age Num 30
Minimum Age Unit Years
Maximum Age Unit Years
Number Of Primary Outcomes To Measure 5
Number Of Secondary Outcomes To Measure 6


Sequence: 30566860
Allocation N/A
Intervention Model Single Group Assignment
Observational Model
Primary Purpose Prevention
Time Perspective
Masking None (Open Label)
Intervention Model Description Single group, cross-over, random order

Responsible Parties

Sequence: 28933254
Responsible Party Type Principal Investigator
Name PKlentrou
Title Professor
Affiliation Brock University

Study References

Sequence: 52166005 Sequence: 52166006 Sequence: 52166007 Sequence: 52166008 Sequence: 52166009 Sequence: 52166010 Sequence: 52166011 Sequence: 52166012
Pmid 25373482 Pmid 17549534 Pmid 24326929 Pmid 18191053 Pmid 21980360 Pmid 20555379 Pmid 32038477 Pmid 7747628
Reference Type background Reference Type background Reference Type background Reference Type background Reference Type background Reference Type background Reference Type background Reference Type background
Citation Mezil YA, Allison D, Kish K, Ditor D, Ward WE, Tsiani E, Klentrou P. Response of Bone Turnover Markers and Cytokines to High-Intensity Low-Impact Exercise. Med Sci Sports Exerc. 2015 Jul;47(7):1495-502. doi: 10.1249/MSS.0000000000000555. Citation Barry DW, Kohrt WM. Acute effects of 2 hours of moderate-intensity cycling on serum parathyroid hormone and calcium. Calcif Tissue Int. 2007 Jun;80(6):359-65. doi: 10.1007/s00223-007-9028-y. Epub 2007 Jun 5. Citation Sherk VD, Barry DW, Villalon KL, Hansen KC, Wolfe P, Kohrt WM. Bone loss over 1 year of training and competition in female cyclists. Clin J Sport Med. 2014 Jul;24(4):331-6. doi: 10.1097/JSM.0000000000000050. Citation Rector RS, Rogers R, Ruebel M, Hinton PS. Participation in road cycling vs running is associated with lower bone mineral density in men. Metabolism. 2008 Feb;57(2):226-32. doi: 10.1016/j.metabol.2007.09.005. Citation Olmedillas H, Gonzalez-Aguero A, Moreno LA, Casajus JA, Vicente-Rodriguez G. Bone related health status in adolescent cyclists. PLoS One. 2011;6(9):e24841. doi: 10.1371/journal.pone.0024841. Epub 2011 Sep 30. Citation Hinton PS, Rolleston A, Rehrer NJ, Hellemans IJ, Miller BF. Bone formation is increased to a greater extent than bone resorption during a cycling stage race. Appl Physiol Nutr Metab. 2010 Jun;35(3):344-9. doi: 10.1139/H10-025. Citation Heikura IA, Burke LM, Hawley JA, Ross ML, Garvican-Lewis L, Sharma AP, McKay AKA, Leckey JJ, Welvaert M, McCall L, Ackerman KE. A Short-Term Ketogenic Diet Impairs Markers of Bone Health in Response to Exercise. Front Endocrinol (Lausanne). 2020 Jan 21;10:880. doi: 10.3389/fendo.2019.00880. eCollection 2019. Citation Robinson TL, Snow-Harter C, Taaffe DR, Gillis D, Shaw J, Marcus R. Gymnasts exhibit higher bone mass than runners despite similar prevalence of amenorrhea and oligomenorrhea. J Bone Miner Res. 1995 Jan;10(1):26-35. doi: 10.1002/jbmr.5650100107.