Table 2.
Protein requirements of female athletes completing aerobic endurance exercise.
| Author/Year (Study Design) | Female Athletes | Menstrual Cycle/Contraceptives | Exercise Protocol | Protein Intake | Control/Comparison Intake | Outcome(s) from Protein Intake 1 |
|---|---|---|---|---|---|---|
| Daily Protein Requirements | ||||||
| Houltham and Rowlands 2014 [39] (cross-over) | 10 competitive cyclists and triathletes 61.3 ± 5.4 kg Body fat % NR |
Mid-follicular (day 4–11) | 90 min cycle intervals at 50–70% VO2max for 3 days | Daily protein intake 2.7 g/kg/day (includes mean 0.75 g/kg whey protein post-exercise) (daily energy: 32% protein, 45% CHO, 23% fat) | Daily protein intake 1.4 g/kg/day (habitual) (daily energy: 16% protein, 54% CHO, 30% fat) | Positive nitrogen balance vs. negative nitrogen balance in control EAR 1.63 g/kg/day RDI 2 2.02 g/kg/day |
| Phillips et al. 1993 [16] (single intervention) 3 | Six recreationally active students 58.1 ± 5.4 kg Body fat 18.8 ± 1.7% |
Mid-follicular (day 4–11) | 90 min run at 65% VO2max | Daily protein intake 0.8 g/kg/day (breakfast energy: 4% protein, 82% CHO, 14% fat) | N/A | Negative nitrogen balance |
| Rowlands and Wadsworth 2011 [42] (cross-over) | 12 competitive cyclists 60.8 ± 3.4 kg Body fat 19 ± 3% |
Six mid-follicular (day 3–7), six hormonal contraceptives |
150 min cycle intervals at 50–90% Wmax day 1, sprint performance test (10 × workload max sprints) days 2 and 4 | Protein blend 0.7 g/kg/h (with 1.4 g/kg/h CHO and 0.26 g/kg/h fat; energy 30% protein, 59% CHO, 11% fat) for 4 h post-exercise with high daily carbohydrate diet | Isocaloric control, protein 0.1 g/kg/h (with 2.1 g/kg/h CHO and 0.26 g/kg/h fat; energy 4% protein, 85% CHO, 11% fat) for 4 h post-exercise with high daily carbohydrate diet | Positive nitrogen balance vs. negative nitrogen balance in control EAR 1.28 g/kg/day RDI 2 1.59 g/kg/day |
| Acute Protein Requirements | ||||||
| Roy et al. 2002 [43] (cross-over) |
10 recreationally trained endurance athletes 61.6 ± 7.6 kg Body fat 21.9 ± 1.1% |
Four mid-follicular (day 4–11), six triphasic OCP |
60 min cycle at 65% VO2peak on days 1, 3, 4 and for 90 min day 6, plus cycle to exhaustion (75% VO2peak) on day 7 | Post-exercise: mixed supplement 0.24 g/kg whey protein (energy 23% protein, 66% CHO, 12% fat) non-caloric placebo 10 h pre-exercise (daily energy: 16% protein, 58% CHO, 26% fat) | Pre-exercise: mixed supplement 0.24 g/kg whey protein 10 h pre-exercise (energy 23% protein, 66% CHO, 12% fat) non-caloric placebo post-exercise (daily energy: 16% protein, 58% CHO, 26% fat) | No differences in nitrogen balance (trend for improved balance on days 6 and 7 with post-exercise) ↓ body mass loss vs. pre-exercise |
EAR, estimated average requirement; CHO, carbohydrate; N/A, not applicable; NR, not reported; OCP, oral contraceptive pill; RDI, recommended dietary intake; VO2max, maximal oxygen uptake; VO2peak, peak oxygen uptake; Wmax, watts maximum. 1 Differences refer to statistical significance reported in the study. 2 RDI calculated as 12% coefficient of variation (1.24 × EAR) in accordance with Rand et al. [35]. 3 Comparison group data did not meet the inclusion criteria.