The effect of carbohydrate supplementation (CHO) on interleukin 2 (IL-2) and interleukin 5 (IL-5) secretion following acute resistance exercise was examined in 9 resistance-trained males. Subjects completed a randomized, double-blind protocol with exercise separated by 14 days. The exercise consisted of a high intensity, short rest interval squat workout. Subjects consumed 1.0 g · kg body mass-1 CHO or an equal volume of placebo (PLC) 10 min prior to and 10 min following exercise. Blood was collected at rest (REST), immediately post exercise (POST), and at 1.5 h of recovery (1.5 h POST). Isolated peripheral blood mononuclear cells were stimulated with PHA and assayed for IL-2 and IL-5 secretion. IL-2 secretion was significantly decreased at POST for both the PLC and CHO groups. However, the degree of decrease was less in the CHO group (16%) than in the PLC group (48%), and this difference was statistically significant. These responses were transient, and the values returned to normal by 1.5 h POST. A mild and transient but significant decrease in IL-5 secretion by the PLC group was observed at POST (26%) compared to REST. No significant decrease was observed in IL-5 secretion for CHO from REST to POST (12%). These data support a possible effect of carbohydrate supplementation on IL-2 and IL-5 secretion following high-intensity resistance exercise.
Influence of Carbohydrate Ingestion on Cytokine Responses Following Acute Resistance Exercise
Marcia A. Chan, Alexander J. Koch, Stephen H. Benedict, and Jeffrey A. Potteiger
Influence of Exercise Time of Day on Salivary Melatonin Responses
Lara A. Carlson, Kaylee M. Pobocik, Michael A. Lawrence, Daniel A. Brazeau, and Alexander J. Koch
Background: Sleep deprivation negatively affects cognition, pain, mood, metabolism, and immunity, which can reduce athletic performance. Melatonin facilitates sleepiness and may be affected by the proximity of exercise to sleep. Purpose: To evaluate the influence of exercise time of day on salivary melatonin (s-melatonin) responses. Methods: Twelve regularly exercising men (age 20.75 [0.62] y, height 1.75 [0.04] m, mass 73.63 [10.43] kg, and maximal oxygen consumption 57.72 [6.11] mL/kg/min) participated in a randomized, crossover design. Subjects completed 3 protocols—morning exercise (09:00 h), afternoon exercise (16:00 h), and no exercise (CON)—at least 5 d apart. Exercise sessions consisted of 30 min of steady-state running at 75% of maximal oxygen consumption. Saliva was collected via passive drool at 20:00, 22:00, and 03:00 h following all sessions. Results: Repeated-measures analysis of variance revealed significant time (P = .001) and condition (P = .026) effects for melatonin. Levels of s-melatonin were significantly increased at 03:00 h compared with 20:00 and 22:00 h for all conditions. Post hoc analyses revealed that s-melatonin at 22:00 h was significantly higher after morning exercise (16.5 [7.5] pg/mL) compared with afternoon exercise (13.7 [6.1] pg/mL) sessions (P = .03), whereas neither exercise condition significantly differed from the control (P > .05). Conclusions: It appears that exercising in the afternoon may blunt melatonin secretion compared with morning exercise. If sleep is an issue, morning exercise may be preferable to afternoon exercise.
Minimal Influence of Carbohydrate Ingestion on the Immune Response Following Acute Resistance Exercise
Alexander J. Koch, Jeffrey A. Potteiger, Marcia A. Chan, Stephen H. Benedict, and Bruce B. Frey
The effect of carbohydrate supplementation (CHO) on the lymphocyte response to acute resistance exercise was examined in 10 resistance-trained males. Subjects completed a randomized double-blind protocol with sessions separated by 14 days. The exercise session consisted of a high intensity, short rest interval squat workout. Subjects consumed 1.0 g · kg body mass−1 CHO or an equal volume of placebo (PLC) 10 min prior to and 10 min following exercise. Blood was collected at rest (REST), immediately post exercise (POST), and at 1.5 hours and 4.0 hours of recovery, and analyzed for plasma glucose, serum cortisol, leukocyte subsets, and phytohemagglutinin (PHA)-stimulated lymphocyte proliferation. A significant Treatment × Time effect was observed for lymphocyte proliferation between CHO and PLC, but post hoc analyses revealed no between-treatment differences at any post-exercise time point. Lymphocyte proliferation was significantly depressed below REST at POST (−39.2% for PLC, −25.7% for CHO). Significant fluctuations in leukocyte subset trafficking were observed for both treatments at POST, 1.5 hours, and 4.0 hours. Plasma glucose was significantly increased POST in CHO compared to PLC. Cortisol was significantly increased from REST to POST in both treatments. These data support a minimal effect of carbohydrate ingestion on the lymphocyte response to high-intensity resistance exercise.
Planned Intensity Reduction to Maintain Repetitions Within Recommended Hypertrophy Range
Helio S. Medeiros Jr, Rafael S. Mello, Mayara Z. Amorim, Alexander J. Koch, and Marco Machado
The authors tested different loading schemes for the number of repetitions completed during multiple sets of resistance exercise.
Twenty-four resistance-trained men (age 24.0 ± 4.5 y, body mass 78.3 ± 10.2 kg, height 177 ± 7 cm) were tested over a 5-wk period. During week 1 a 10-repetition maximum (10RM) in the leg press was determined. During weeks 2–5 subjects completed 4 bouts of leg presses, in a randomized fashion, consisting of 4 sets with 60 s of interset rest. Set 1 of each bout was performed with 10RM, with differing intensity for sets 2–4 as follows: (1) 10RM load for all sets (CON), (2) 5% load reduction after each set (RED 5), (3) 10% load reduction after each set (RED 10), and (4) 15% load reduction after each set (RED 15).
Significant (P < .05) decreases in repetitions completed across sets were observed in CON (sets 2, 3, and 4) and RED 5 (sets 3 and 4). Significant increases in repetitions completed across sets (2, 3, and 4) were observed in RED 10 and RED 15 (P < .05). RED 5 (8.3 ± 0.9 repetitions) and RED 10 (12.0 ± 1.1 repetitions) allowed subjects to maintain the majority (>60%) of sets in the range of 8–12 repetitions, whereas both CON and RED 15 resulted in <50% of sets in the range of 8–12 repetitions, with the majority of sets performed <8 repetitions for CON and >12 repetitions for RED 15.
Reducing load 5–10% in each set should allow maintenance of 8–12RM loads for most sets of resistance exercise.
Carbohydrate Supplementation Attenuates Muscle Glycogen Loss during Acute Bouts of Resistance Exercise
G. Gregory Haff, Alexander J. Koch, Jeffrey A. Potteiger, Karen E. Kuphal, Lawrence M. Magee, Samuel B. Green, and John J. Jakicic
The effects of carbohydrate (CHO) supplementation on muscle glycogen and resistance exercise performance were examined with eight highly resistance trained males (mean ± SEM, age: 24.3 ± 1.1 years, height: 171.9±2.0 cm, body mass: 85.7 ± 3.5 kg; experience 9.9 ± 2.0 years). Subjects participated in a randomized, double blind protocol with testing sessions separated by 7 days. Testing consisted of an initial isokinetic leg exercise before and after an isotonic resistance exercise (IRT) session consisting of 3 leg exercises lasting ~39 min. Subjects consumed a CHO (1.0 g CHO ·kg body mass−1) or placebo treatment (PLC), prior to and every 10-min (0.5 g CHO ·kg body mass−1) during the IRT. Muscle tissue was obtained from the m vastus lateralis after a supine rest (REST) immediately after the initial isokinetic test (POST-ISO) and immediately after the IRT (POST-IRT). The CHO treatment elicited significantly less muscle glycogen degradation from the POST-ISO to POST-IRT (126.9 ± 6.5 to 109.7 ± 7.1 mmol·kg wet weight−1) compared to PLC (121.4±8.1 to 88.3±6.0 mmol·kg wet weight−1). There were no differences in isokinetic performance between the treatments. The results of this investigation indicate that the consumption of a CHO beverage can attenuate the decrease in muscle glycogen associated with isotonic resistance exercise but does not enhance the performance of isokinetic leg exercise.
Oral Creatine Supplementation Augments the Repeated Bout Effect
Kelle F. T. Veggi, Marco Machado, Alexander J. Koch, Sandro C. Santana, Sedison S. Oliveira, and Michael J. Stec
We examined the effects of creatine supplementation on the response to repeated bouts of resistance exercise.
Young men (24.1 ± 5.2 yr) were divided into Creatine (CM, n = 9) and Placebo (PL, n = 9) groups. On day (D) 1 and D15, subjects performed four sets of bicep curls at 75% 1-RM to concentric failure. On D8-D13, subjects consumed either 20g/d creatine monohydrate or placebo. Muscle soreness and elbow joint range of motion (ROM) were assessed on D1-D5 and D15-D19. Serum creatine kinase activity (CK) was assessed on D1, D3, D5, D15, D17, and D19.
The first exercise bout produced increases in muscle soreness and CK, and decreases in ROM in both groups (p < .001). The second bout produced lesser rises in serum CK, muscle soreness, and a lesser decrease in ROM (bout effect, p < .01 for all), with greater attenuation of these damage markers in CM than PL. CK levels on D17 were lower (+110% over D15 for CM vs. +343% for PL), muscle soreness from D15–19 was lower (–75% for CM vs. –56% for PL compared with first bout), and elbow ROM was decreased in PL, but not CM on D16 (p < .05 for all).
Creatine supplementation provides an additive effect on blunting the rise of muscle damage markers following a repeated bout of resistance exercise. The mechanism by which creatine augments the repeated bout effect is unknown but is likely due to a combination of creatine’s multifaceted functions.
Carbohydrate Supplementation and Immune Responses after Acute Exhaustive Resistance Exercise
Lara A. Carlson, Samuel Headley, Jason DeBruin, Alex P. Tuckow, Alexander J. Koch, and Robert W. Kenefick
This investigation sought to study changes in leukocyte subsets after an acute bout of resistance exercise (ARE) and to determine whether ingestion of carbohydrate (CHO) could attenuate those immune responses. Nine male track-and-field athletes (21.1 ± 1.4 yr, 177.2 ± 5.5 cm, 80.9 ± 9.7 kg, 8.7% ± 3.8% fat) and 10 male ice hockey athletes (21.0 ± 2.2 yr, 174.3 ± 6.2 cm, 79.6 ±11.1 kg, 13.9% ± 3.73% fat) participated in 2 different ARE protocols. Both experiments employed a counterbalanced double-blind research design, wherein participants consumed either a CHO (1 g/kg body weight) or placebo beverage before, during, and after a weight-lifting session. Serum cortisol decreased (p < .05) at 90 min into recovery compared with immediately postexercise. Plasma lactate, total leukocyte, neutrophil, and monocyte concentrations increased (p < .05) from baseline to immediately postexercise. Lymphocytes decreased significantly (p < .05) from baseline to 90 min postexercise. Lymphocytes were lower (p < .05) for the CHO condition than for placebo. The findings of this study indicate the following: ARE appears to evoke changes in immune cells similar to those previously reported during endurance exercise, and CHO ingestion attenuates lymphocytosis after ARE.
Planned Load Reduction Versus Fixed Load: A Strategy to Reduce the Perception of Effort With Similar Improvements in Hypertrophy and Strength
Bruce M. Lima, Rafael S. Amancio, Diacre S. Gonçalves, Alexander J. Koch, Victor M. Curty, and Marco Machado
Purpose: To compare muscle thickness and 10-repetition maximum (10RM) between no load reduction and load reductions during 16 wk of resistance training. Methods: A total of 21 moderately trained men (age 23.2 [4.2] y, body mass 75.1 [7.6] kg, height 175  cm) were randomized into 1 of 3 exercise groups: control (CON, n = 7), all sets with 10RM load; 5% load reduction (RED 5, n = 7); and 10% load reduction (RED 10, n = 7) for set 2 and set 3. The resistance training program consisted of completing 3 sets each of biceps and Scott curls, performed to volitional fatigue 3 d·wk−1. Results: Volume load lifted over the 16 wk was similar among groups (CON, 38,495  kg; RED 5, 37,388  kg; RED 10, 42,634  kg; P = .094). Muscle thickness increased in all groups (P < .001), with no differences noted among groups (P = .976). Biceps-curl and Scott-curl 10RM increased in all groups (P < .001), with no differences noted among groups (Scott curl P = .238; biceps curl P = .401). Rating of perceived exertion (RPE) was significantly lower for RED 10 (6.8 [0.1]) than for CON (7.0 [0.1]; P < .001) or RED 5 (7.1 [0.1]; P = .001) for the Scott curl. RPE was significantly lower (P = .001) for the biceps curl in RED 10 (6.8 [0.3]) than in CON (7.3 [0.9]), with neither group different from RED 5 (7.0 [0.1]). Conclusions: Load reduction did not yield a difference in hypertrophy or 10RM as compared with CON. However, RED 10 induced a significantly lower RPE. Thus, load reduction may be a beneficial strategy to reduce the perception of effort during training while achieving similar improvements in hypertrophy and strength.
Caffeine Does Not Augment Markers of Muscle Damage or Leukocytosis Following Resistance Exercise
Marco Machado, Alexander J. Koch, Jeffrey M. Willardson, Frederico C. dos Santos, Victor M. Curty, and Lucas N. Pereira
The purpose of this study was to evaluate the effects of caffeine ingestion before a resistance exercise session on markers of muscle damage (CK, LDH, ALT, AST) and leukocyte levels.
Fifteen soccer athletes completed two resistance exercise sessions that differed only in the ingestion of caffeine or a placebo preworkout.
CK concentration increased significantly following the caffeine session (415.8 ± 62.8 to 542.0 ± 73.5) and the placebo session (411.5 ± 43.3 to 545.8 ± 59.9), with no significant differences between sessions. Similarly, LDH concentration increased significantly following the caffeine session (377.5 ± 18.0 to 580.5 ± 36.1) and the placebo session (384.8 ± 13.9 to 570.4 ± 36.1), with no significant differences between sessions. Both sessions resulted in significant increases in the total leukocyte count (caffeine = 6.24 ± 2.08 to 8.84 ± 3.41; placebo = 6.36 ± 2.34 to 8.77 ± 3.20), neutrophils (caffeine = 3.37 ± 0.13 to 5.15 ± 0.28; placebo = 3.46 ± 0.17 to 5.12 ± 0.24), lymphocytes (caffeine = 2.19 ± 0.091 to 2.78 ± 0.10; placebo = 2.17 ± 0.100 to 2.75 ± 0.11), and monocytes (caffeine = 0.53 ± 0.02 to 0.72 ± 0.06; placebo = 0.56 ± 0.03 to 0.69 ± 0.04), with no significant differences between sessions.
Ingestion of caffeine at 4.5 mg⋅kg-1 did not augment markers of muscle damage or leukocyte levels above that which occurs through resistance exercise alone.