Does a woman’s menstrual cycle affect her running performance?

Acclaimed trainer explains the significant impact of hormones on female physiology

CHAMPAIGN, IL—While a man’s hormonal system remains relatively stable, a female’s hormonal system is constantly changing. According to Jason Karp, PhD, an exercise physiologist and 2011 IDEA Personal Trainer of the Year, hormonal fluctuations can affect how women will respond and adapt to training. “The phase of the menstrual cycle significantly affects a female runner’s hormonal environment and therefore her physiology,” Karp explains. “Any physiological changes resulting from menstrual cycle-induced fluctuations in estrogen and progesterone are exacerbated during exercise, especially if it’s intense.”

In the forthcoming book Running for Women (Human Kinetics, 2012), Karp and coauthor Carolyn Smith, MD, explain how various aspects of physiology are affected by the phase of the menstrual cycle, including oxygen consumption, body temperature, and metabolism.

Oxygen Consumption

“Progesterone stimulates ventilation independent of the intensity of the run, which can increase the perception of effort since runners typically link their perception of effort to how much they’re breathing,” Karp explains. “Breathing is greater during the luteal phase, when progesterone concentration is highest, making women feel more winded during luteal-phase workouts than in follicular-phase workouts.” The increased breathing during the luteal phase may also increase the oxygen demand of breathing since the muscles responsible for breathing need oxygen to work just as leg muscles do. More oxygen being used by breathing muscles means less oxygen is available for the leg muscles to aid with running.

Body Temperature
Body temperature changes rhythmically throughout the menstrual cycle, peaking during the luteal phase in response to the surge in progesterone. “A higher body temperature during the luteal phase makes it harder to run in the heat, because you don’t begin sweating to dissipate heat until you have reached a higher body temperature,” Karp says. “Women also have a decreased ability to dilate the small blood vessels under the skin, which compromises their ability to release heat to the environment.” Thus, long, intense workouts and races in the heat, such as half marathons and marathons, can be more difficult during the luteal phase of the cycle.

Metabolism
“Menstrual-phase variations in running performance may largely be a consequence of changes to exercise metabolism stimulated by the fluctuations in estrogen and progesterone concentrations,” Karp says. “The magnitude of increase in these hormones between menstrual phases and the ratio of estrogen to progesterone concentration appear to be factors determining an effect on metabolism.” Research suggests that estrogen may improve endurance performance by altering carbohydrate, fat, and protein metabolism, and progesterone often acts antagonistically to estrogen. Estrogen promotes both the availability of glucose and uptake of glucose into slow-twitch muscle fibers, providing the fuel during short-duration exercise.

According to Karp, a woman’s responsiveness to strength training can also be influenced by the menstrual cycle. “One study found that weight training every second day during the follicular phase and once per week during the luteal phase of the menstrual cycle increased maximal quadriceps strength by 32.6 percent compared to just 13.1 percent by training once every third day over the whole menstrual cycle,” Karp says.

Running for Women presents guidelines for tailoring training to the menstrual cycle for maximum response and adaptation as well as determining the best times to perform the various types of training. The book also contains recommendations for modifying workouts and training programs for all stages of the life span, including pregnancy, menopause, and postmenopause.

For more information, see Running for Women.

About the Authors

Jason Karp, PhD, is an exercise physiologist, a running and fitness expert, and the 2011 IDEA Personal Trainer of the Year. He offers science-based coaching to runners of all levels and consulting to coaches through his company, RunCoachJason.com. He is in demand as a presenter at numerous coaching, fitness, and academic conferences, including U.S. Track & Field and Cross Country Coaches Association, American College of Sports Medicine, American Society of Exercise Physiologists, and IDEA World Fitness Convention. Karp is also a prolific writer, with four books and more than 200 articles published in magazines, including Runner’s World, Running Times, Shape, Oxygen, Self, and Ultra-Fit.

Karp has enjoyed success coaching at high school, college, and club levels. He has taught USA Track & Field’s highest level of coaching certification and was an instructor at the USATF/U.S. Olympic Committee’s Emerging Elite Coaches Camp at the U.S. Olympic Training Center. The founder and coach of REVO₂LT running team and a competitive runner himself, Dr. Karp is a USA Track & Field-certified coach and is sponsored by PowerBar as a member of PowerBar Team Elite.

Karp received his PhD in exercise physiology with a physiology minor from Indiana University in 2007, his master’s degree in kinesiology from the University of Calgary in 1997, and his bachelor’s degree in exercise and sport science with an English minor from Pennsylvania State University in 1995. Dr. Karp has taught exercise physiology and biomechanics at several universities and taught in the fitness certificate program at the University of California at Berkeley. He is currently an adjunct faculty member at Miramar College in San Diego, where he teaches applied exercise physiology.

Carolyn Smith, MD, is a family practice and sports medicine physician who serves as director of the student health service at Marquette University and head medical team physician for the department of intercollegiate athletics. She also maintains her teaching interests in her role as medical director for the athletic training education program.

After a postcollegiate career running shorter distances, Smith embraced ultrarunning in 2002 and has enjoyed success in distances ranging from the 50-mile run to the 24-hour run. She is a former 24-hour and 100K national champion. She has had the privilege of representing the United States on two 24-hour national teams (2005, 2007) and is a six-time 100K national team member (2004, 2007, 2008, 2009, 2010, and 2011). 

As a runner, she is a national age-group record holder and a member of the 100-kilometer national ultramarathon team. In 2009, she held the fastest time in the world for the 50-mile ultramarathon and was ranked No. 1 in that event in the United States. She represented the United States for the sixth time in the 100-Kilometer World Cup, which was held in the Netherlands in 2011. In 2011 she set a national age-group record for the 12-hour run, finishing first among all participants in the FANS 12-hour ultramarathon in Minnesota, running 83 miles in 12 hours—more than 12 miles ahead of the second-place finisher. 

In addition to a medical degree from the University of Illinois, Smith holds a master’s degree from Northern Illinois University and a bachelor’s degree from the University of Wisconsin, both in exercise physiology. Following a faculty position with the St. Michael Hospital residency program in Milwaukee, and the Medical College of Wisconsin, Smith joined the Marquette University student health service in 2002.

Contents

Part I Physiology

Chapter 1 Performance Factors and Gender Differences 

Chapter 2 Menstrual Cycle, Hormones, and Performance

Chapter 3 Pregnancy

Chapter 4 Menopause

Chapter 5 Older Runners

Part II Training

Chapter 6 Training Components

Chapter 7 Base Building

Chapter 8 Acidosis (Lactate) Threshold Training

Chapter 9 Aerobic Power Training for VO₂max

Chapter 10 Strength and Speed Training

Chapter 11 Building Your Training Program

Part III Health and Wellness

Chapter 12 Female Athlete Triad

Chapter 13 Injuries and Female Runners

Chapter 14 Performance Nutrition and Female Runners

Questions for Jason Karp

• Why are stress fractures more prevalent in female runners than male runners?
• Why does running in adolescence offer the greatest opportunity to increase bone mass?
• What is the female athlete triad and how can you determine if you’re at risk?
• Why should the frequency and intensity of training be done in small, incremental steps?
• Why does the percentage of body fat and skinfold thickness in specific areas of the body (e.g., below the scapula on the back, above the hip bone, and the abdomen) influence a female runner’s race performance and the speed at which she trains?    
• Research suggests women have more slow-twitch muscle fibers than men. Why does this contribute to greater long-endurance performance for females but compromise sprint performance?
• Why do female runners have a high incidence of menstrual irregularities?
• Why should older runners pay more attention to their fluid intake?
• Describe acidosis (lactate) threshold training and how it benefits runners.
• Explain VO₂max and how to determine your maximum heart rate.
• How is lung function after exercise affected by the phase of the menstrual cycle?
• Why do women have better athletic performance during times of the menstrual cycle when estrogen is the dominant hormone and the worst performance when progesterone is the dominant hormone?

Background Facts

• Studies have shown that estrogen influences pulmonary function, body temperature, and plasma volume of the blood; the latter affects fluid retention and hydration status. The effects of estrogen on fluid distribution and control of body temperature may make running in the heat more challenging for women than for men.
• A woman’s wider hips create a more pronounced angle between the pelvis and the knee (called the quadriceps angle or Q-angle) because the femur (thigh bone) is positioned at a more oblique angle than the femur of a man. A large Q-angle causes the knee bone (patella) to be more off center from the tibia (shin bone). Tracking of the patella against the femur is dependent on direction of the force produced by the quadriceps. With a wide Q-angle, there is more lateral movement of the patella as the quadriceps contract, which can put female runners at a greater risk for knee injuries than male runners. A larger Q-angle can also put women at a mechanical disadvantage when running.
• Women’s anatomy affects their stride mechanics. Research has shown that female runners take shorter strides than male runners when running at the same speed. Since running speed is equal to stride length multiplied by stride rate, female runners compensate for the shorter stride length by having a quicker stride rate than male runners.
• Studies have confirmed that female runners are more likely to develop a stress fracture in the absence of regular menstrual cycles. In a study that investigated a group of collegiate runners, stress fractures occurred in 49% of women with very irregular menses (0 to 5 menses per year) compared with 29% of women with regular menses (10 to 13 menses per year).
• Since bone is lost rapidly in the years surrounding menopause, it is important that measures be taken to reduce the loss of bone. Numerous studies have demonstrated the beneficial effects of regular running on reducing the rate of bone loss in postmenopausal women. A longitudinal study in female masters runners also demonstrated that levels of bone mineral density can be maintained with consistent running activities.
• Even when similarly trained, female runners have smaller hearts than male runners. The larger heart gives men a greater stroke volume and cardiac output, contributing to a greater VO₂max. Men also have a larger blood volume and more hemoglobin in their blood to transport oxygen. Together, the larger heart, greater blood volume, and greater blood hemoglobin concentration create a cardiovascular system that supplies more blood and oxygen to the running muscles, giving men greater cardiovascular endurance than women.

Facts taken from Running for Women.

Endorsements

"Using meticulous research, Karp and Smith have created a practical and intriguing masterpiece for female runners of all ages and abilities. Highly recommended!"

Lorraine Moller

Boston Marathon Winner

Olympic Marathon Medalist

Cofounder of the Lydiard Foundation
Author of On the Wings of Mercury

“In Running for Women, Carolyn Smith and Jason Karp combine scientific research with realistic guidelines that all women can follow to combat the effects of aging.”

Meghan Arbogast

Four-Time Qualifier to the Olympic Marathon Trials

Team USA Leader at World 100K Championships

World-Record Holder for 50+ Age Group in the 100K

“In Running for Women, Dr. Karp and Dr. Smith provide women and their coaches a clear path to success and enjoyment in training and racing."

Joe Compagni

Director and Head Coach

Men’s and Women’s Track and Field and Cross Country

Monmouth University