Despite the broad benefits of exercise to bone health, athletes from some sports fare better than others.  Athletic training and performance can also be completely derailed by bone stress injuries, which have multifactorial contributors of which bone health is key. Energy availability, bone-loading exercise and vitamin D are known to influence bone health, but even with these optimized, bone issues can still remain. 

Research studies observing endurance training (running and cycling) have noted an acute drop in serum ionized calcium early in an exercise bout. This change is associated with an increased parathyroid hormone concentration and increases in the bone breakdown marker C-terminal telopeptide of type I collagen. This has given rise to the theory that bone is being used as a reservoir of calcium to maintain stable levels in the blood. It is thought that the calcium “borrowed” over time for this purpose may not be fully “paid back” and may contribute to bone health issues in these athletes.

The theory is supported by a series of studies showing the drop in serum ionized calcium is attenuated by providing pre-exercise calcium intake, either intravenously or orally through a supplement or diet. This finding may provide an additional strategy for athletes to protect their bone health over and above adequate energy intake, overall daily calcium intake and vitamin D status. These studies, however, have focused on single exercise bouts of cycling or running and do not represent the more typical training pattern of athletes who may train two to three times each day. 

In our study, published in Medicine & Science in Sports & Exercise_®, we aimed to replicate a more typical training day by including more than one training session. We also chose a novel sport by using rowing, a non-weight-bearing sport where bone stress injuries have a negative effect on the ability to train and perform to potential. This is an issue from the sub-elite to the elite level within the sport. This study is unique in that top-caliber athletes from the Australian rowing team were able to participate. Unfortunately, due to COVID-19 travel restrictions at the time of the study, only male rowers were able to participate.

The current study adds to the research by extending monitoring over two training session, representing a more typical training day. Dietary intake was standardized for the 24 hours prior to the test, and all food was provided on the testing days. Pre-exercise calcium intake was set at 1,000 mg for the high-calcium group and less than 10 mg for the control group, and was easily achieved and tolerated through diet. This was provided in the form of a bowl of Bircher muesli and a toasted ham-and-cheese sandwich. The low calcium intake was achieved using a nondairy milk and yogurt, and vegan cheese.

The key findings were that, rather than the effect diminishing when multiple training sessions were undertaken, these changes are maintained through a training day and become potentially more important given the attenuation of bone breakdown over 7+ hours rather than 1-2. While the question remains as to whether this is ultimately beneficial to bone health over weeks and months, it adds a valuable step forward in our understanding and provides a safe new strategy for athletes to try. 

Bronwen Lundy, Ph.D., is a sports dietitian who has been embedded in the Australian rowing team for the past 11 years. She has worked at the Australian Institute of Sport, the English Institute of Sport and with professional sports teams in the Australian rugby union and rugby league competitions. She is a member and previous director of Sports Dietitians Australia. She has recently completed a Ph.D. under the supervision of Louise Burke and John Hawley investigating nutrition factors relating to bone injury in rowing. 

Louise Burke, Ph.D., is a sports dietitian with 40 years of experience in the education and counselling of elite athletes. She was head of sports nutrition at the Australian Institute of Sport and the team dietitian for the Australian Olympic Teams (1996-2012). She is currently chair in sports nutrition in the Mary MacKillop Institute of Health Research at Australian Catholic University with over 350 papers in peer-reviewed journals and is an editor of the International Journal of Sport Nutrition and Exercise Metabolism. Louise was a founding member of the Executive of Sports Dietitians Australia and is a director of the IOC Diploma in Sports Nutrition and ACSM member. She was awarded a Medal of the Order of Australia in 2009 for her contribution to sports nutrition.

Viewpoints presented in SMB commentaries reflect opinions of the authors and do not necessarily represent ACSM positions or policies. Active Voice authors who have received financial or other considerations from a commercial entity associated with their topic must disclose such relationships at the time they accept an invitation to write for SMB.

ACSM is excited to announce a fresh new look for Exercise and Sport Sciences Reviews (ESSR), thanks to the diligent work of the publication team and longtime ACSM designer Dave Brewer. The new cover made its debut on the January 2023 issue.

ESSR had its start in 1972 as annual hardcover volume and in 2000 transitioned to a quarterly journal, a publication schedule it retains to this day. The latest redesign took into account extensive reader surveys and competitor analyses.

Then came the brainstorming: “The first step was to deconstruct the old cover down to the basic elements and then experimenting with different groupings/positions with the journal title,” Dave says.

After much ideating and iterating, Dave came up with a series of conceptual designs that he shared with the team. Once these were narrowed down to a few top picks, and after incorporating further feedback, he shared them with a wider group of constituents for final approval.

The design the team landed on has been well-received within the ACSM community.

“I’m thrilled with the new and contemporary cover of Exercise and Sport Sciences Reviews,” says ESSR Editor-in-Chief Sandra Hunter, Ph.D., FACSM. “The design team did a fabulous job … resulting in a strong cover redesign that appropriately houses the cutting-edge and forward-thinking review articles in sports medicine and exercise science. It’s an exciting time to be a contributor to the high-quality journals of ACSM.”

ACSM Publications Committee Chair Karyn Hamilton, Ph.D., R.D., FACSM, agrees.

“What an exciting time for ACSM Membership!” she says. “Exercise and Sport Sciences Reviews has a brand new look, a talented new editor-in-chief with outstanding new ideas for the journal, and a continued commitment to publishing the most relevant scientific, medical and research-based topics emerging in the field.”

Read the New Issue

Approximately 80% of jobs in the United States are predominantly sedentary. Sedentary work time is also increasing worldwide. National and global policy guidelines recommend breaking up sedentary work time to improve population health and reduce premature mortality. However, policies and job demands requiring workers to remain at their desks, along with limited funds and space for exercise equipment, can impede efforts to break up sedentary work time. Under-desk pedaling devices could help address these impediments as they can be used without leaving one’s desk, and their cost and space requirements are similar to office chairs. However, the optimal under-desk pedaling intensity level to enable concurrent office work among physically inactive adults has not been well explored.

In our study, published in Medicine & Science in Sports & Exercise_®, we tested if physically inactive adults could perform office work tasks while concurrently using an under-desk pedaling device at low intensity levels. To help understand if under-desk pedaling is feasible for diverse workers, we recruited equal numbers of men and women, older and younger working-aged adults, and normal weight and overweight/obese adults. Ninety-six adults completed the study in a controlled laboratory setting over a two-hour period. We measured the adults’ performance on typing, reading, logical reasoning and phone tasks while engaged in seated pedaling at two intensity settings (17 and 25 watts) and while seated without pedaling. We also measured adults’ perceived comfort while pedaling and working.

We found that physically inactive adults obtained equivalent work performance scores on typing, reading, logical reasoning and phone tasks across all pedaling and non-pedaling conditions. Differences in adults’ age, sex and body mass index did not modify the pattern of equivalent work performance we observed across the pedaling and non-pedaling conditions. Pedaling at both intensity settings appeared feasible for most physically inactive adults, as adherence to the 17 and 25 watt pedaling intensities exceeded 95%. Adults reported greater comfort while completing work tasks during the lower intensity setting of 17 watts.

Our findings suggest that physically inactive adults can productively perform work tasks while using an under-desk pedaling device at low intensity levels. As adults reported more comfort completing work tasks during the lower intensity condition, future desk-pedaling programs may benefit from recommending a starting intensity level of about 17 watts.

We hope our findings contribute to efforts to implement and evaluate under-desk pedaling devices on a larger scale over extended time periods. Many under-desk pedaling devices provide real-time tracking of pedaling duration and speed — enabling these devices to simultaneously provide feedback for employees and data for program evaluation. These dynamic measurement features of under-desk pedaling devices could help inform next steps to optimize their implementation and use. For instance, ongoing pedaling tracking could provide data on the volume of pedaling that predicts optimal productivity and health outcomes, or the effects of praise and/or incentives on pedaling volume. Continued efforts to implement and evaluate under-desk pedaling devices could reduce health risks of sedentary work time and contribute toward building activity-supportive workplace environments and cultures. 

Liza S. Rovniak, Ph.D., MPH, is an associate professor of medicine and public health sciences at the Pennsylvania State University College of Medicine. Her research focuses on designing environments and policies to sustain physical activity, healthy eating and other behaviors. Using an ecological framework and emphasizing interdisciplinary collaborations, Dr. Rovniak conducts clinical trials and epidemiological research across diverse populations and settings to explore how to facilitate long-term health behavior change. Dr. Rovniak is an ACSM member.

Viewpoints presented in SMB commentaries reflect opinions of the authors and do not necessarily represent ACSM positions or policies. Active Voice authors who have received financial or other considerations from a commercial entity associated with their topic must disclose such relationships at the time they accept an invitation to write for SMB.