Skeletal muscle is the engine that drives human health and performance and is influenced by modifiable healthy lifestyle behaviors (i.e., nutrition and exercise) and non-modifiable factors (i.e., sex and age). It is well-established that resistance exercise stimulates the synthesis of skeletal muscle protein (especially the force-generating myofibrillar fraction) for up to 48 hours. This ultimately provides the basis supporting increases in muscle mass (i.e., hypertrophy) with training. However, establishing whether timing and/or sex influences the relationship between exercise-induced increases in muscle protein synthesis and muscle mass has yet to be determined.

To address the sex-imbalance in previous male-oriented research, our study published in the June 2022 issue of Medicine & Science in Sports & Exercise_® (MSSE) used equal numbers of recreationally active 18-30 year old females and males who performed 8 weeks of resistance exercise to stimulate muscle growth. Orally ingested “heavy water” — i.e., water whose hydrogen atoms possess extra neutrons — allowed us to assess the synthesis of the myofibrillar protein fraction over 48 hours in an exercise-naïve (i.e., first training bout) and accustomed (i.e., last training bout) state outside of the laboratory. This method allowed us to capture the complete duration for which protein synthesis is elevated after exercise while also controlling for energy and dietary protein intake. This “free-living” technique provided a unique opportunity to assess how these acute training stimuli contribute to or help predict muscle growth.

We observed that muscle hypertrophy at the fiber (cross-sectional area) and whole muscle (thickness) level was similarly increased by training in both females and males. Although exercise-induced increases in myofibrillar protein synthesis were slightly greater in males (~23%), this did not translate to statistically greater gains in muscle mass. Importantly, post-exercise rates of myofibrillar protein synthesis were similar after the first and last training bouts, but positively correlated with growth only when the muscle became accustomed to the exercise stimulus (i.e., trained state) in both sexes. These findings are consistent with some previous research and highlight the need to allow a muscle to become conditioned to a novel exercise stimulus before its growth potential can be determined from changes in muscle protein synthesis.

Females are often unrepresented and excluded in exercise science research, frequently due to perceived challenges in having to account for potential effects of menstrual cycle perturbations on metabolism. Our findings in the follicular phase build off previous foundational research in males and can provide the basis for future research to confirm similar results in females across phases of the menstrual cycle or when using hormonal contraception. Further research exploring potential sex-based differences are essential to ensure current exercise and/or nutritional recommendations based primarily on research in males are valid for females. Learning from experience, our results suggest that perceived sex-based differences are of little consequence to predicting the hypertrophic potential of resistance exercise and the mechanisms governing exercise-induced myofibrillar protein synthesis.

Sidney Abou Sawan, Ph.D., is a postdoctoral fellow at the Department of Kinesiology at McMaster University. His research interests revolve around understanding the mechanisms underpinning skeletal muscle plasticity and the associated impact on health and performance in response to human nutrition and exercise.

Daniel Moore, Ph.D., is an associate professor in the Faculty of Kinesiology and Physical Education at the University of Toronto. His research studies how exercise and nutrition impact whole-body and skeletal muscle protein metabolism and the nutritional requirement for dietary protein in active populations across the lifespan. He is an ACSM member and past recipient of the Peter J. Reeds Young Investigator Award from the American Society for 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.

In the last decade, various forms of interval training have gained popularity. In fact, high-intensity interval training has been in the top five in ACSM’s Annual Worldwide Survey of Fitness Trends since 2014. Sprint interval training has also gained popularity in recent years. These two forms of interval training are used in many different populations, including patients in rehabilitation programs, athletes looking to optimize their performance and the general public seeking to improve or maintain their cardiorespiratory fitness.

Sprint interval training has been shown to be an effective form of training when it comes to increasing maximal oxygen consumption (VO_2max). Despite the small amount of time required (~10 minutes), the training-induced effects after sprint interval training interventions are equivalent to those after exercise programs that include traditional endurance exercises with a time commitment three to four times longer per session.

Previous research has shown that sprint interval training has a pronounced effect on peripheral adaptations. Such adaptations include muscle capillarization and mitochondrial content and function, and a variety of genes involved in the ability of skeletal muscle to obtain and use oxygen during exercise respond positively to sprint interval training. However, less is known about the central hemodynamic effects after sprint interval training. Central adaptations include factors responsible for oxygen delivery to the working muscle. Cardiac size and structure, total blood volume and hemoglobin mass are all part of central hemodynamics.

In our study, published in the June issue of Medicine & Science in Sports & Exercise_®, we investigated how these central hemodynamic factors respond to a six-week training intervention consisting of sprint interval training. Each training session consisted of 10 minutes of low-intensity cycling interspersed with three 30-second all-out sprints. Our main interest was which factors responsible for oxygen delivery (total hemoglobin mass, blood volume, maximal cardiac output) would contribute to the expected improvements in cardiorespiratory fitness. The study involved younger, healthy participants who were active, but did not follow any structured training programs before the intervention. As expected, the participants obtained a substantial increase in VO_2max (10.3%) after the training intervention. Specific hemodynamic factors that improved were total hemoglobin mass, maximal cardiac output and total blood volume, where total hemoglobin mass in particular correlated with improvement in VO_2max. These findings suggest that sprint interval training-induced improvements in VO_2max are mediated by both peripheral and central factors. Both the changes in VO_2max and many of the underlying adaptive mechanism are thus comparable to those of conventional endurance training.

In our view, this means that the similarity between sprint interval training and conventional endurance exercise when it comes to training effects and the adaptations mediating the effects is higher than previously thought. Practically, that would allow for a wider and more interchangeable use of intervals in training programs without the fear of “missing out” on central hemodynamical training effects.

The next question we need to answer is, “How is it that two training modalities as different from one another as sprint interval training and traditional endurance training lead to the same physiological changes?

Mirko Mandić, M.Sc., is a Ph.D. student at the Division of Clinical Physiology at Karolinska Institutet in Sweden. His research focuses on central hemodynamical adaptations to exercise, with a special focus on the adaptations of blood volume, circulation and the heart.

Eric Rullman, M.D., Ph.D., is a cardiologist and physiologist working at the Karolinska University Hospital in addition to his position as a researcher at the Division of Clinical Physiology at Karolinska Institutet. Dr. Rullman’s research is focused on the regulatory mechanisms limiting physical capacity in healthy individuals and their prognostic potential in heart disease, from transcriptional networks to cardiac output.

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.

Take a look at the mass media and social media you are currently watching or reading in the month of May. What do you see? Most likely, you see articles mentioning Mental Health Awareness Month, Asian American and Pacific Islander Heritage Month, and exercise or physical activity recommendations in the era of the COVID-19 pandemic. If you are asked to incorporate these three elements into a practical program in a real-world setting, you may wonder how you could put the pieces together. The answer is simple — integrating Eastern mindfulness movements (e.g., tai chi, qigong, yoga) into our exercise routines. Mindful movements are exercises that bring your attention to your breathing and the movements of your body; oftentimes they lead to a meditative state of mind. Hence, they are also known as “meditative movements.”

COVID-19 poses a significant risk, particularly older adults and those with cardiometabolic diseases. The response to the pandemic has also led to a reduction in individuals’ physical activity, an increase in sedentary behavior, and a decrease in social contact and support — which in turn has caused mental health issues among numerous people since the start of the pandemic. Therefore, it is imperative we promote individuals’ mental health and well-being, ideally through holistic and feasible approaches that can be done at home or in community centers.

Tai chi, qigong and yoga, the three most popular mind-body practices in the United States, can be excellent choices. These mindful movements are known to increase strength and flexibility, improve sleep quality and alleviate pain. They also provide significant benefits to mental health, such as increasing self-awareness, creating a sense of calmness, reducing stress and anxiety, and enhancing mood. A scientific review in 2018 confirmed that tai chi, qigong and yoga could be effective non-pharmacological modalities in the management of depression and anxiety — and unfortunately, depressive symptoms increased by 25% worldwide during the pandemic.

Let us take tai chi, a form of mind-body exercise that originated in China, as an example. Tai chi comprises Chinese martial arts and meditative movements that enhance the well-being of the mind and body. The slow, continuous and mindful movements and dance-like postures flow into each other, making tai chi an ideal exercise modality to practice at home or in small groups. Prior to the pandemic, people practiced tai chi in small groups in a variety of settings, like parks, YMCAs and community centers. Research evidence suggests tai chi programs have positive effects on individuals’ immune systems, inflammation reduction, rehabilitation in respiratory diseases and emotional improvement. Also, practicing tai chi requires limited space and no extra equipment, so it can be practiced at home or in a nearby park, making it possible for us to maintain an active lifestyle during the pandemic and cope with COVID-19 adversities.

Since the outbreak of COVID-19, researchers and practitioners have been creative in taking advantage of emerging technology to deliver tai chi programs remotely to groups of learners. Delivering tai chi programs virtually via Zoom meetings has increased in popularity during the pandemic. For example, the co-author of this blog, a certified tai chi instructor, taught a virtual evidence-based fall-prevention program, Tai Ji Quan: Moving for Better Balance, to a group of older adults in 2021 and another Yang-style, 24 forms tai chi program for nearly 20 middle-aged women in 2022 using Zoom. Both classes were well received by the participants. One of the most frequent comments received from the participants was the benefit of stress reduction.

Given the ubiquitous nature of modern-day technology, professionals and practitioners are seeking to leverage several e-health technologies (e.g., smartphone apps and virtual reality) to help individuals practice tai chi with a virtual instructor. For example, 7 Minute Chi is one of the most popular tai chi apps on the Apple Store. The movements are easy to follow without in-person instructions, and it is beginner friendly. On the other side, the Learn Tai Chi app is ideal for people who have experience practicing tai chi.

Virtual reality is considered a cutting-edge technology, possessing great potential in promoting a tai chi practice due to its fun and interactive features. Guided Tai Chi is a virtual reality game that is available on Oculus Quest 2. It guides players through over 200 tai chi-inspired workouts ranging from 3 minutes up to 60 minutes across 20 arcade sessions (i.e., virtual natural environments). The game uses Quest’s motion controllers or players’ hand-tracking to instruct the person through slow and thoughtful motions. It features several tai chi styles of movements with a virtual instructor. Individuals learn the basic movements by following visual instructions, including connecting dots. The user can enjoy relaxing exercises, combining elements of several tai chi styles. In addition to a fully immersive virtual reality tai chi game, Tai Chi for Beginners is another option for the non-immersive virtual reality game on the Xbox gaming platform. This game has eight easy-to-follow lessons teaching tai chi postures with clear, step-by-step instructions. It should be noted that most, if not all, tai chi apps and virtual reality games usually charge some fees upon purchase.

To celebrate Mental Health Awareness Month and Asian American and Pacific Islander Heritage Month in May, we as kinesiologists and health professionals can introduce Eastern mindfulness movements into exercise routines with the goal of promoting mental health and well-being among our communities. Although we only use tai chi as an example in this blog, we can also practice other Eastern mindfulness movements, such as yoga and qigong, through similar approaches. The development of holistic exercise and meditative programs will inform non-pharmacologic strategies for mental health promotion during the pandemic and beyond.

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Zan Gao, Ph.D., is a professor at the School of Kinesiology in University of Minnesota-Twin Cities, specializing in physical activity and health promotion. Dr. Gao’s research has primarily focused on promoting health through population-based physical activity interventions with emerging technologies such as active video games, virtual reality and health wearables. He has published three edited books, 28 book chapters, and 150 research articles in peer-reviewed journals. Dr. Gao has been the recipient of several international/national awards and the principal investigator of National Institute of Health and Robert Wood Johnson Foundation research grants. He is currently serving as an editorial board member for five professional journals and the associate editor for the Journal of Health and Sports Science and Research Quarterly for Exercise and Sports. Dr. Gao’s google h-index is 44. He is a fellow of American College of Sports Medicine_^®, and a fellow of the SHAPE America! Research Council.

Yingying Chen, DNP, R.N., is a clinical assistant professor and is leading the Master of Science in Aging in Mandarin program at Edson College of Nursing and Health Innovation at Arizona State University. She received her initial nursing degree from Fujian University of Traditional Chinese Medicine and later completed the RN-BSN program at Saint Mary’s University of Minnesota. In 2018, she obtained her doctoral degree in integrative health and healing at the University of Minnesota’s School of Nursing. She has nearly a decade of clinical nursing experience working with older adults in various health care settings in both U.S. and China. She has a keen interest in holistic therapies and is a certified tai chi instructor and a reiki master. Dr. Chen’s greatest passion is to bridge health care between the West and the East and improve quality of life for older adults.

In 2022 we celebrate the 25th anniversary of the HERITAGE (HEalth, RIsk factors, exercise Training And GEnetics) Family Study. The May issue of Medicine & Science in Sports & Exercise_® (MSSE) highlights a multitude of the more than 200 publications and other dissemination products from data generated from this groundbreaking and important research program. The HERITAGE study described the role of genetics in cardiovascular, metabolic and hormonal responses to exercise training in Black and white adults and children. It was the first study of its kind and the largest exercise-focused study ever that recruited Black and white people for hereditary comparison. While revolutionary in its purpose, scope and implementation, two-and-a-half decades later, some language in the HERITAGE study protocol paper raises eyebrows at best and expressions of concern at worst.

We have dedicated our professional service and scholarly activities to improving social justice, equity, diversity and inclusion in science, education and our professional activities within and external to the American College of Sports Medicine_® (ACSM). Thus, we were invited to contribute a commentary to preface the papers in the MSSE supplement. The invitation to comment was motivated by concern expressed by a group of students and their faculty instructor in a kinesiology department at an R1 institution in the United States who read the HERITAGE study protocol paper as part of a course. These individuals found the paper’s language to be racist and insulting to people who value racial diversity in research and in society as a whole. ACSM’s leadership decided to be proactive in prefacing the current supplement by addressing concerns about the description of Black families in the original paper and the potential of this supplement to reinforce negative stereotypes about Black people.

Approaching this topic took careful consideration in order to celebrate the knowledge produced by this rigorous and historic research, coupled with the stellar reputations of the scientists who delivered this work, while recognizing the problematic language in the original paper. We invited two other contributors, a biological anthropologist who studies primate and human evolution (Nina Jablonski), and another exercise physiologist who uses human and cell models to focus on vascular health in Blacks (Michael Brown), to join us in authoring this paper.

In our commentary, we acknowledge and celebrate the many contributions of the HERITAGE study while drawing attention to the fact that language in the original paper could add to the historic harm that Blacks have experienced in science and practice. We cite examples of two historic incidences in research and medicine that led to many Black people’s unwillingness to participate in scientific investigations based on their mistrust and concerns about their treatment by health care systems and providers, as well as researchers. The commentary indicates that over the 25 years since the HERITAGE study, society has witnessed myriad accomplishments in research and medical practice. We must never lose sight of the accomplishments in social justice, diversity, equity and inclusion within our professions. We must also continue the ethical imperative that everyone persists in implementing these important features while designing, conducting and disseminating research and delivering quality clinical care.

NiCole R. Keith, Ph.D., FACSM, is a research scientist in the Center for Aging Research, a Regenstrief Institute Investigator, a professor of kinesiology and the associate dean of faculty affairs in the School of Health and Human Sciences at Indiana University-Purdue University in Indianapolis, Indiana. She was the 2020-21 president of ACSM. Dr. Keith addresses heath equity by researching methods through which physical activity can positively influence the health outcomes of individuals who are underrepresented minorities as well as those who reside in socioeconomically challenged communities.

W. Larry Kenney, Ph.D., FACSM, FAPS, is the Marie Underhill Noll Chair in Human Performance and professor of physiology and kinesiology at the Pennsylvania State University. Dr. Kenney studies human responses to exercise, heat and cold stress, and dehydration as well as the biophysics of heat exchange between humans and the environment. He served as ACSM president from 2003 to 2004. He is also the primary author of Physiology of Sport and Exercise, a bestselling textbook in exercise physiology now in its eighth edition.

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.