Table 2 Summary of Relevant Literature Pertaining to Nutrient Timing and Exercise
| AUTHORS/REFERENCE | SUBJECTS | SUPPLEMENT/DOSAGE | TIME OF ADMINISTRATION | TYPE OF EX. | SAMPLES | MAJOR OUTCOMES |
|---|---|---|---|---|---|---|
| Biolo et al. 1997[47] | 6 untrained males | - Infusion of balanced AA mixture (0.15 g·kg-1·h-1 for 3 h) |
Two conditions: - REST - Post-ex. | - Leg resistance exercise routine |
- Muscle biopsies - Arteriovenous blood samples for 3 h post-ex. |
- PRO synthesis post-ex. > rest - AA transport increased 30–100% post-ex. compared to rest- PRO intake immediately post-ex. may be more anabolic than other times |
| Kobayashi et al. 2003[30] | 10 normal Yorkshire swine | Continuous infusion of a mixed AA solution | Infusion began 2 h into dialysis and for remaining 2 h | NONE | - A/V samples and biopsies were taken throughout entire protocol. |
- Signal to change [AA] was plasma [AA] - Decrease in PRO synthesis led to decrease in eIF2B activation - Intramuscular [AA] did not change |
| Bohe et al. 2003[59] |
- 21 healthy subjects (11 M, 10 F) - 29 ± 2 yrs | - Mixed AA infusion at varying rates (44–261 mg AA·kg-1·h-1) | Study attempted to determine any dose-response relationship to PRO synthesis | NONE |
- A/V blood samples pre-infusion and for next 6.5 h - 4 biopsies at 30, 180, 240 and 390 min. |
- Myofibrillar, sarcoplasmic, and mitochondrial PRO synthesis was similar - PRO synthesis is regulated by extracellular [EAA] and becomes saturated at high concentrations. - A dose-dependent relationship exists between [AA] and PRO synthesis. |
| Bohe et al. 2001[58] | 6 (5 M, 1 F) normal, healthy adults | - Infusion (162 mg·kg-1·h-1) of mixed AA | 6 h infusion period at constant rate | NONE |
- A/V blood samples over 9 h - Muscle biopsies to determine AA incorporation |
- PRO synthesis increase ~2.8× basal value within 2 h of infusion - PRO synthesis then declined rapidly - AA availability may be limited by transport of AA into muscle |
| Paddon-Jones et al. 2003[45] | 12 healthy male and females |
Two conditions: - Saline infusion + 15 g EAA solution - 27 h cortisol infusion + 15 g EAA solution | - Measurements were taken pre- and post-consumption of EAA solution. | NONE |
- A/V blood before and after EAA ingestion. - 3 biopsies were taken (pre-/post-infusion, supplement consumption) |
- Cortisol increased arterial, venous and muscle intracellular AA concentrations. - EAAs improved muscle protein anabolism during acute hypercortisolemia and may help minimize muscle loss following debilitating injury. |
| Levenhagen et al. 2002[65] | 5 M, 5 F tested 3× with 4 week wash-out |
Oral doses of: - Placebo (P) - 8 g CHO + 3 g fat (SUPP) - 8 g CHO + 3 g fat + 10 g PRO (SUPP+PRO) | Immediately after exercise | 60-min. cycling @ 60% max VO2 and 180 min recovery period. |
- Blood every 15 min. before ex. - Arterial and venous blood every 30 min. post-ex. for 180 min. |
- In compared to NO or SUPP, SUPP + PRO resulted in a net uptake of EAA and increase in leg and whole-body protein synthesis - AA are more important than energy for post-ex. repair and growth. |
| Levenhagen et al. 2001[56] | 5 M, 5 F | 10 g PRO + 8 g CHO + 3 g Fat | Oral administration immediate or 3 h post-ex. | 60 min cycling @ 60% max VO2 |
- Blood every 15 min. before ex. - Arterial and venous blood every 30 min. post-ex. For 180 min. | - Early intake of a nutrient supplement enhances greater accretion of whole body and leg protein compared to late ingestion. |
| Tarnopolsky et al. 1997[66] | 8 M, 8 F trained endurance athletes |
3 groups: - Placebo (PLA) - CHO (1 g/kg) - CHO (0.75 g/kg) + PRO (0.1 g/kg) + Fat (0.02 g/kg) |
Two oral doses of each supplement: - Immediately post-ex. - 1 h post-ex. | - 90 min. cycle ergometer at 65% max VO2 |
- Blood samples were given pre-ex., during ex. And 3 h and 4 h post-ex. - 3 post-ex biopsies (immediate, 1 h 4 h) |
- Glucose and insulin increased in both trials post-ex w/no gender effect - Glycogen resynthesis increased in both trials vs. PLA w/no gender effect |
| Borsheim et al. 2004[52] | 16 (10 M, 6 F) recreationally active subjects |
Two conditions: - 100 g CHO - Placebo (PLA) solution | Oral ingestion at 1 h post-ex. |
- Leg press (10 × 8 reps) @ 80% 1 Rmprior to 4 h bed rest - 2 min. rest between sets |
- Arteriovenous blood every ~20 min. for 4 h post-ex. - 4 biopsies (1 pre/3 post-ex.) |
- CHO ingestion improved PRO balance after RE - Effect, however, was minor and delayed compared with ingestion of AA |
| Roy et al. 2000[67] | 10 young (19–21 y), healthy males |
- Placebo (PLC) - CHO (1 g/kg) - CHO/PRO/Fat (1 g/kg) | Immediately post-ex and 1 h post-ex. |
- 9 resistance training exercises - 3 sets @ 80% 1 RM |
- Arterial/venous blood samples every ~20 min. post-ex. - 24 h urine | - Nonoxidative leucine disposal (marker of protein synthesis) was increased 4 h for CHO/PRO/Fat and CHO immediately and 1 h following resistance training. |
| Tipton et al. 2001[3] | 3 M, 3 F completed one PRE and POST session |
EAC: 6 g EAA + 35 g CHO PLA: Sweetened water |
PRE: EAC solution pre-ex. POST: EAC solution post-ex. |
- Leg press and leg ext. 8–10 sets × 8 reps @ 80% 1 RM - 2 min. rest between sets |
- 16 venous and arterial blood samples pre-, during and post-ex. Over 180 min. - Muscle biopsies @ -60, 0, 60 and 120 min. |
- AA delivery increased w/ex. And 2 h post-ex. In both trials - PRO synthesis increased compared to post - PRE AA uptake was increased 160% more than in POST - EAC promoted positive N balance in both trials |
| Borsheim et al. 2004[57] | 8 subjects participated in both trials |
Oral doses of: - 77.4 g CHO + 17.5 g Whey + 4.9 g AA (PAAC) - 100 g CHO (P) | 1 h post-exercise | - Resistance exercise | - Femoral artery, vein and muscle biopsies were collected for 3 h post-ex. |
- PAAC caused an immediate increase and a delayed increase in protein balance - PAAC stimulated a greater increase in PRO synthesis vs. CHO after resistance training. |
| Tipton et al. 1999[54] | 3 M, 3 F |
Three solutions: - 40 g CHO (PLA) - 40 g mixed AA - 40 g EAA | - Continual (100 mL) consumption every 15–20 min. from 1 h post-ex. To 4 h post-ex. |
- Leg Press (5 × 10 reps @ 75% 1 RM) - Squat, leg curls/ext. (4 × 8 reps @ 75% 1 RM |
- Arteriovenous blood at -120, 30, 220, 260 and 270 min. - Muscle biopsy was taken at 270 min. |
- Both MAA and EAA increased net protein balance - No difference in protein balance between MAA and EAA suggests no need for NEAA to cause protein synthesis |
| Tipton et al. 2003[60] | 4 F, 3 M |
Two conditions: - REST - REST + EAA+ EX | - 15 g EAA solution before and after exercise session |
- 8 × 8 reps @ 80% 1 RM - 2 min. rest between sets | - Five biopsies and A/V blood samples were taken throughout entire 24 h protocol. |
- AA exchange (ES – REST) @ 3 h and 24 h was not different - Acute response of muscle to EAA intake + EX is additive to rest and thus reflects 24 h response. |
| Tipton et al. 2004[62] | 23 healthy untrained young males and females |
Three conditions: - Placebo (PLA) - Casein (CAS) - Whey protein (WP) | 1 h post-ex. |
- Leg ext. 10 × 8 reps @ 80% 1 RM - 2 min. rest between sets |
- Femoral A/V blood samples for 3 h post-ex. - 4 biopsies (pre-, 1 h, 2 h, 5 h post-ex.) |
- Both WP and CAS increased PRO balance to promote PRO synthesis - AA uptake was increased after exercise in both groups |
| Ratamess et al. 2003[37] | 17 resistance-trained men |
Two conditions: - Placebo (PLA) - AA supplementation |
- Immediately post-workout when training - Mornings of no training |
- 4 d/wk RE program for 4 wks - 2 wk high-intensity phases | - Strength, power and endurance were determined at end of week |
- Reduction in strength and power was attenuated by AA supplementation - High intensity, moderate volume RE is effective to increase strength and power. |
| Rasmussen et al. 2000[51] | 3 M, 3 F in postabsorptive state and recreationally active |
- Placebo drink (PLA) - EAA+CHO drink (35 g CHO+6 g EAA) |
Two conditions: - PLA 1 h post-ex + EAA+CHO 3 h post-ex - EAA+CHO 1 h post-ex. + PLA 3 h post-ex. |
- 8–10 sets × 8 reps @ 80% 1 RM - 2 min. rest between sets |
- 11 arteriovenous blood over 7 h time span. - Muscle biopsies at 45 min, 2 h and 4 h post-ex. |
- No change in PLA - EAA+CHO increased PRO balance and PRO SYN 1 h and 3 h post-ex. - No increase in PS and PRO balance at 3 h vs. 1 h with both > than pre-ex. |
| Miller et al. 2003[53] | 6 M, 4 F |
- CHO alone - AA alone - CHO + mixed AAs (MIX)* *50% EAA according to wt. |
- Two drinks at 1 h and 2 h post-ex. - Infusion was started 1 h prior to exercise and continue 4 h post-ex. |
- 8–10 sets × 10 reps of leg press and leg ext. @ 75% 1 RM - 2 min. rest between sets |
- Biopsies at 30, 90, 150 and 210 min. post-ex. - Arteriovenous blood for 4 h post-ex. |
- Combined effects of CHO Å after resistance exercise is equivalent to their independent effects. - Prior intake of AA+CHO does not diminish metabolic response to a second comparable dose 1 h later. |
| Borsheim et al. 2002[1] | 3 M, 3 F recreationally active | - 6 g Essential amino acids (EAA) | - Two oral doses of 6 g EAA at 1 h and 2 h post-ex |
- 8–10 sets × 10 reps of leg press and leg ext. @ 80% 1 RM - 2 min. rest between sets |
- 4 muscle biopsies were provided post-ex - Femoral artery and venous blood samples ~every 20 min. for 4 h post-ex |
- PRO balance increased in response to both drinks and decreased when [AA] returned to basal levels - Non-essential AA are not necessary for increasing PRO balance - PRO synthesis is dose-dependent of [EAA] |
| Boirie et al. 1997[68] | 16 young (24 ± 4 yrs) healthy subjects |
Five conditions: - 30 g whey - 43 g casein (equal [Leu]) - 30 g unlabeled whey - 43 g unlabeled casein - 30 g unlabeled casein |
- Feeding Trial - No exercise - All conditions were ingested at same time | NONE | - A/V blood samples for entire 7 h time period |
- CAS had prolonged plateau of high [AA] inhibiting PRO breakdown by 34% - WP caused dramatic increase in [AA] causing 68% increase in PRO synthesis - Speed of PRO digestion and AA absorption have major effect on protein synthesis. |
| Dangin et al. 2003[69] |
- 9 elderly (72 ± 1 yrs) - 6 young (24 ± 1 yrs) |
- Casein protein (CAS) - Isonitrogenous whey w/CAS (WPiC) - Isonitrogenous whey w/leucine (WPiL) |
- Feeding Trial - No exercise | NONE |
- A/V blood samples - Muscle biopsies |
- Whey digested faster than CAS - PRO breakdown was not different - PRO synthesis was highest with WP vs. CAS irrespective of age |
| Dangin et al. 2001[70] | 22 healthy young males (25 ± 1 yrs) |
- 30 g casein - 30 g free AA mimic casein - 30 g whey - Repeated small doses of whey |
- Feeding Trial - No exercise | NONE | - A/V blood samples for entire 7 h time period |
- "Fast" meals (whey and free AA) caused strong, rapid increase of [AA] - Moderate increase in [AA] with "slow" meals and stayed elevated longer - 7 h Leu balance was higher after slow vs. fast meals |
| Volpi et al. 1998[71] | (71 ± 2 yrs) | - Infusion of an AA mixture | - Postabsorptive vs. Infusion state | NONE |
- Muscle PRO synthesis and breakdown - A/V blood - Muscle biopsies |
- Muscle PRO synthesis increased in response to AA infusion - Muscle PRO breakdown did not change thus increasing PRO balance. |
| Paddon-Jones et al. 2004[72] |
- 6 Young (34 ± 4 yrs) - 7 Older (67 ± 2 yrs) | - One single oral dose of 15 g EAA solution | - Pre-/post-supplementation measures were taken. | NONE | - A/V blood samples and muscle biopsies were taken for 3 h pre- and 4 h post-supplementation |
- EAA increased PRO synthesis in both young and old - Increase in [AA] was slower in elderly subjects but remained elevated for a longer period. - No overall diff. in PRO synthesis between young and old. |
| Esmarck et al. 2001[55] | 13 M older individuals (74.1 ± 1 yr) | - Liquid supplement (10 g PRO + 7 g CHO + 3 g fat) |
- Immediately post training session (P0) - 2 h post training session (P2) | - 12 week RE program (3×/week) |
- Body comp. (DEXA) - Hypertrophy via MRI, and muscle biopsies - Isokinetic strength |
- P0 > P2 for cross-sect. area and mean fiber area - Similar change in strength - Immediate protein supplementation post-ex. promotes more growth in elderly males |
| Volpi et al. 2000[73] |
4 M, 1 F young (30 ± 3 yrs) 4 M, 1 F elderly (72 ± 1 yrs) |
- Resting or basal phase - 40 g glucose + 40 g mixed AA |
Subjects completed a: - 300 min. resting period - 180 min. supplement period | NONE |
- AV samples every 10 min. last 60 min. - 4 biopsies in 480 min. |
- AA turnover was similar in young and old. - PRO synthesis with high [AA] and [insulin] was blunted in elderly compared to young. |
| Volpi et al. 2003[74] | 14 elderly adults (70 ± 2 yrs) |
- 18 g EAA - 40 g Mixed AA (18 g EAA+22 g NEAA) | Small oral boluses every 10 min. for 3 h | NONE |
Protein metabolism was measured via: - A/V blood - Muscle biopsies |
- AA balance increased in similar amounts from resting in both conditions - EAA are responsible for PRO synthesis in elderly |
| Andersen et al. 2005[63] | - Isoenergetic CHO vs. PRO |
- Before and after RE - Morning on non-training days | 14-week RE program |
- Muscle cross-sectional area - Strength |
- PRO increased Type I/II fibers more than CHO - Squat jump height increased in PRO vs. CHO |
