Nutritional aspects of women strength athletes
J S Volek, C E Forsythe, and W J Kraemer
Strength training elicits sports related and health benefits for both men and women. Although sexual dimorphism is observed in exercise metabolism, there is little information outlining the specific nutritional needs of women strength athletes. Many women athletes restrict energy intake, specifically fat consumption, in order to modify body composition, but this nutritional practice is often counter‐productive. Compared to men, women appear to be less reliant on glycogen during exercise and less responsive to carbohydrate mediated glycogen synthesis during recovery. Female strength athletes may require more protein than their sedentary and endurance training counterparts to attain positive nitrogen balance and promote protein synthesis. Therefore, women strength athletes should put less emphasis on a very high carbohydrate intake and more emphasis on quality protein and fat consumption in the context of energy balance to enhance adaptations to training and improve general health. Attention to timing of nutrient ingestion, macronutrient quality, and dietary supplementation (for example, creatine) are briefly discussed as important components of a nutritionally adequate and effective strength training diet for women.
- Strength training = good
- Women utilize more fats and less carbs than men during exercise
- +ve nitrogen balance required for LBM gains
- Adequate fat intake required for health gains and optimal hormonal profile
- Carbs essential for performance -emphasize mico-nutrient-rich and unprocessed whole foods as source of carbs
- Protein recommendation: 1.4–1.8 g/kg
- No adverse effects of high protein intake in healthy individuals
- Good idea to pad workouts with protein-rich meals
- Creatine = good
Strength training benefits
- Health gains
- Improvements in performance
Increase in bone mass and lean mass,9 improved body composition (due to decreased fat mass), cardiovascular fitness, strength, and an enhanced sense of well being.
Importance of nutrition
- Fuel for activities
- Needed to ensure strength and muscular adaptations
Women and strength training
- women’s physiological response similar to men’s
- greater initial increase of strength due to relatively lower baseline strength levels
- decreased testosterone = limiting factor for gains
The common fear that women will become too bulky or large with strength training is not physiologically possible and should not dissuade women from engaging in this mode of exercise.
Gender differences in exercise metabolism
- use more fat and less carbs than men during submaximal exercise
- larger area of TYPE 1 fibers = increased Intramuscular fat storage
- use less glycogen than men during resistance exercise
- expend less energy and lower EPOC in response to resistance exercise(RE) vs Men
This gender difference in carbohydrate metabolism during resistance exercise may also be explained by the fact that women usually have a greater capacity for lipid breakdown and oxidation compared to men,20 such that glycogen is spared more in women than in men.
Energy intake (EI)
- +ve nitrogen balance required for optimal LBM gains
- -ve energy balance = increased protein utilization = reduced gains
- emphasis on energy balance is particularly important for female athletes as large majority are constantly looking for ways to cut weight and/or in a -ve energy balance = suboptimal gains
- low EI = fatigue, deterioration of performance and mood, reduced T3 and T4 levels, slower recovery, increased bone de-mineralization and risk of fractures, reproductive dysfunction.
Female athletes are commonly reported as maintaining negative energy balance,49 due to factors such as preoccupation with body image and societal pressures to achieve a low body fat percentage.50,51 These self reported energy deficits, although not always accompanied by weight loss, are often associated with irregular menstrual cycles indicating that energy intake may not be appropriate.
Although female athletes typically use energy restriction as a means to improve body composition, female elite athletes with larger or more frequent daily energy deficits have higher body fat percentages,54 perhaps due to an adaptive reduction in resting metabolic rate.
- Matched caloric expenditure: RE and Endurance Exercise (EE) increases EPOC and resting energy expenditure (REE) in women by same amount.
- RE elevates 24h EE = requires increased EI to prevent -ve energy balance
The best time for women to increase food consumption seems to be during and after exercise to take advantage of the enhanced sensitivity of skeletal muscle to take up glucose and amino acids. Attention to energy needs during and following exercise should be of high priority to ensure optimal athletic performance.
How much energy is needed?
Total Daily Expenditure
= Rest Energy Expenditure X Physical Activity Level + Thermic Effect of Activity
Thermic Effect of activity dependent on duration and instensity of training session.
The phase of the menstrual cycle may also be taken into consideration when estimating energy requirements. In adult pre‐menopausal women, REE is shown to be slightly increased in the luteal phase compared to the follicular phase.73 Women may be encouraged to consume slightly more energy during the follicular phase of their menstrual cycle to ensure optimal athletic performance
- carbs required to maintain glycogen stores
- glycogen stores = muscle fuel
- importance of muscle glycogen = popularity of high carb diet
High carb diets and women strength athletes – suboptimal?
- women utilize less glycogen during RE than men
- synthesize less glycogen from equal amount of carbs
- impractical to use weight based carb-loading protocol for women due to smaller size
- in the long run sacrificing fats and protein for carbs = -ve nitrogen balance and hormonal imbalance
- strength athletes do not require as much carbs as endurance athletes
- emphasize micro-nutrient-rich and whole foods as sources for carbs
- Current protein recommendations based on men studies
- Women may oxidise less protein during exercise = lower protein requirement
- Unlike men, women have a greater increase in MPS when AAs are provided after exercise = advantageous to consume more protein post-RE
- Based on men studies – good idea to ingest protein pre and post exercise
- High protein intake not detrimental for bone but may be beneficial
- No evidence of increased risk of renal problems, CVD or cancer
- Generally – Animal protein superior because of better bio availability
The argument against this statement is that even if there is a limit to gains in lean mass with high protein ingestion, increasing evidence shows that dietary substitution of carbohydrate with protein results in a variety of favourable health effects including enhanced weight loss, reduction in truncal adipose tissue, optimal maintenance of blood glucose, and improved lipid profile.
- insufficient fat intake = reduced IMTG stores = reduced performance
- easy source of calories
- Fat intake >15% helpful in preventing female athlete triad and maintaining healthy mood and hormonal profile
- improves anaerobic performances
- increases strength and LBM gains from RE