Journal Title (Medline/Pubmed accepted abbreviation): Sports Med.
Page Numbers: 861-882
Many exercise studies are performed on males alone, although subtle yet distinct differences have been observed between males and females in response to exercise. This review highlights the differences between the genders and offers specific recommendations for female athletes to optimize their post-workout routine. These recommendations will help female athletes stay healthy and be best prepared for their next exercise bout.
Differences in females’ optimal post-workout protocols stem from differences in body size (smaller on average), body composition (more fat and less muscle on average, different placement of fat), hormones, and typical dietary habits.
Females are generally more efficient at burning fat for energy. Consequently, they have an advantage over males in endurance events 66 km or longer. Higher levels of estrogen may increase the body’s sensitivity to catecholamines (hormones that relay signals to other parts of the body about energy metabolism, ex. epinephrine or adrenaline). This phenomenon perhaps contributes to an increase in rates of fat oxidation and a decrease on dependence of glycogen from the liver. In fact, due to cyclic fluctuations of estrogen during the menstrual cycle, the woman’s place in her cycle may affect energy metabolism during exercise. A higher estrogen to progesterone ratio (in the early follicular phase) may promote fatty acid oxidation while a lower estrogen to progesterone ratio (in the luteal phase) may increase the rate of oxidation of amino acids for energy during exercise. Many confounding factors make scientific investigations challenging, and it is unknown if (or how) a female should alter her diet or post-workout regimen to optimize recovery based on her place in her cycle.
To compensate for the increased rate of fat oxidation during exercise, females also show increased rate of fat synthesis after exercise. This phenomenon could help explain why it is sometimes more difficult for females than males to lose unwanted fat mass.
In regard to post-workout recovery beverages, there does not seem to be a difference in rate of glycogen replenishment between males and females. High carbohydrate meals/beverages that are moderate to high glycemic index are recommended to maximize the rate of glycogen synthesis. For daily nutrition, it is recommended that female athletes consume at least 5 g of carbohydrates per kg of body weight per day, with up to 6-8 g/kg with intense training. In addition, athletes should consume a higher amount of protein than their non-athlete counterparts: 1.2-1.4 g/kg compared to 0.8 g/kg for the non-athlete. For strength-seeking athletes, up to 1.4-1.8 g/kg is recommended. Inaccurately, lipids (fats) are sometimes not recognized by female athletes as being a very important, essential part of the diet. About 30% of calories from lipids is recommended, especially for athletes involved in endurance events. Despite their overall nutritional importance, lipids are not recommended immediately after a workout.
Micronutrients are very important, too, especially iron for menstruating females. Animal sources of protein provide iron, vitamins B1, B2, B12, and D, zinc, calcium, and phosphorus. Vegetarians and vegans must be extra prudent in obtaining these nutrients.
Females athletes involved in sports that emphasize smallness (for example, gymnastics and cross country), are constantly in negative energy balance (i.e. they are not consuming enough total calories). This causes their bodies to not be in peak physical condition, increasing fatigue and soreness and compromising performance. The typical female athlete requires approximately 2300-2500 kcal/day (for a 115 lb. female), or about 45-50 kcal/kg body weight. Those involved in intense training, esp. marathon running, may require up to 4000 kcal/day.
An attenuated response in plasma creatine kinase concentrations was noted in females in response to aerobic exercise in several studies. Creatine kinase is a marker of inflammation and muscle damage and, therefore, this suggests that females had an attenuated inflammatory response. Moreover, a handful of studies have shown that females have a faster recovery from strength exercise. This phenomenon can be explained in part by animal studies that have shown estrogen to protect the animal against inflammation. These results have not been confirmed in humans. Because of the differences in post-workout inflammatory responses, it is hypothesized that post-workout ice baths may be more beneficial for women than men for enhancing the rate of recovery, though future research would need to confirm that.
Female diets tend to be lower in calcium, and this could be detrimental to bone health. Calcium is recommended immediately post-workout to maximize the rate of bone remodeling. It is recommended that adult women consume at least 1000 mg/day and female adolescents consume at least 1300 mg/day. Greater increases in lean body mass (muscle and bone) were seen with a dairy-based post-workout beverage in one study compared to a beverage with less calcium. Restricted energy intake also increases the risk for bone fractures. To maintain bone health, athletes should also assure that they are meeting their daily requirements of vitamin D, especially those that live in northern Canada or Nordic regions or that train inside (because of the more infrequent exposure to the sun).
Active recovery is when an athlete participates in 2 exercise sessions within 1 hr of one another. Some studies show that active recovery speeds total recovery compared to passive recovery and that females may be able to reap more gains from this strategy than males. The authors recommend that females that engage in active recovery maintain moderate intensity activity in between two high intensity workouts that are within 1 hr of one another.
One study showed that wearing compression socks during the recovery period improved circulation in women and that this may improve overall recovery.
The body employs natural processes of thermoregulation (control of body temperature) during and after exercise like promoting blood flow and sweating. Women’s bodies are slightly different than males’ in terms of composition and physiology, and females generally are slower at bringing body temperature back down to their baseline. With that said, post-workout recommendations are similar for males and females: adequately replenish lost fluids and electrolytes. One group recommends cool water (12-15°C or 54-59°F) with 2% carbohydrate and 1.15 g/mL of sodium for fast recovery. Cold water immersion after exercise in order to quicken the return to normal body temperature may be of greater benefit to females to males, but more research is required to confirm this hypothesis.