Charles L. Dumke
Column-editor : Debra M. Vinci
Trevor L. Gillum, Charles L. Dumke and Brent C. Ruby
To describe the degrees of muscle-glycogen depletion and resynthesis in response to a half Ironman triathlon.
One male subject (38 years of age) completed the Grand Columbian half Ironman triathlon (1.9-km swim, 90-km bike, 21.1-km run, Coulee City, Wash). Three muscle biopsies were obtained from his right vastus lateralis (prerace, immediately postrace, and 4 hours postrace). Prerace and postrace body weight were recorded, in addition to macronutrient consumption before, during, and after the race. Energy expenditure and whole-body substrate oxidation were estimated from linear regression established from laboratory trials (watts and run pace relative to VO2 and VCO2).
Body weight decreased 3.8 kg from prerace to postrace. Estimated CHO energy expenditure was 10,003 kJ for the bike segment and 5759 kJ for the run segment of the race. The athlete consumed 308 g of exogenous CHO (liquid and gel; 1.21 g CHO/min) during the race. Muscle glycogen decreased from 227.1 prerace to 38.6 mmol · kg wet weight−1 · h−1 postrace. During the 4 hours postrace, the athlete consumed a mixed diet (471 g CHO, 15 g fat, 64 g protein), which included liquid CHO sources and a meal. The calculated rate of muscle-glycogen resynthesis was 4.1 mmol · kg wet weight−1 · h−1.
Completing a half Ironman triathlon depends on a high rate of muscle glycogenolysis, which demonstrates the importance of exogenous carbohydrate intake during the race. In addition, rates of muscle-glycogen resynthesis might be dampened by the eccentric damage resulting from the run portion of the race.
Sean R. Schumm, N. Travis Triplett, Jeffrey M. McBride and Charles L. Dumke
This investigation examined the anabolic-hormone response to carbohydrate (CHO) supplementation at rest and after resistance exercise. Nine recreationally trained men randomly underwent 4 testing conditions: rest with placebo (RPL), rest with CHO (RCHO), resistance exercise with placebo (EPL), and resistance exercise with CHO (ECHO). The resistance-exercise protocol was four sets of Smith machine squats with a 10-repetition-maximum load, with 90-s rests between sets. Participants then consumed either a placebo or CHO (24% CHO, 1.5 g/kg) drink. Blood was taken before exercise (Pre), immediately after testing (Post), and then 15 (15P), 30 (30P), and 60 (60P) min after drink ingestion. Blood was analyzed for cortisol, glucose, insulin, and total testosterone (TTST). Cortisol did not change significantly in any condition. Glucose concentrations increased significantly from Pre to 15P and 30P during RCHO and Pre to 15P, 30P, and 60P in ECHO (p ≤&.05). Insulin concentrations increased significantly from Pre to 15P, 30P, and 60P in the RCHO and ECHO conditions (p ≤&.05). There were no significant changes in TTST concentrations during RPL or RCHO. Both EPL and ECHO demonstrated a significant elevation in TTST concentrations from Pre to Post (p ≤&.05). During ECHO, TTST concentrations at 60P were significantly lower than Pre levels (p ≤&.05), but there were no significant treatment differences in TTST concentrations at any time point during the EPL and ECHO conditions. Ingesting CHO after resistance exercise resulted in decreased TTST concentrations during recovery, although the mechanism is unclear.
Michael J. Cramer, Charles L. Dumke, Walter S. Hailes, John S. Cuddy and Brent C. Ruby
A variety of dietary choices are marketed to enhance glycogen recovery after physical activity. Past research informs recommendations regarding the timing, dose, and nutrient compositions to facilitate glycogen recovery. This study examined the effects of isoenergetic sport supplements (SS) vs. fast food (FF) on glycogen recovery and exercise performance. Eleven males completed two experimental trials in a randomized, counterbalanced order. Each trial included a 90-min glycogen depletion ride followed by a 4-hr recovery period. Absolute amounts of macronutrients (1.54 ± 0.27 g·kg-1 carbohydrate, 0.24 ± 0.04 g·kg fat-1, and 0.18 ± 0.03g·kg protein-1) as either SS or FF were provided at 0 and 2 hr. Muscle biopsies were collected from the vastus lateralis at 0 and 4 hr post exercise. Blood samples were analyzed at 0, 30, 60, 120, 150, 180, and 240 min post exercise for insulin and glucose, with blood lipids analyzed at 0 and 240 min. A 20k time-trial (TT) was completed following the final muscle biopsy. There were no differences in the blood glucose and insulin responses. Similarly, rates of glycogen recovery were not different across the diets (6.9 ± 1.7 and 7.9 ± 2.4 mmol·kg wet weight- 1·hr-1 for SS and FF, respectively). There was also no difference across the diets for TT performance (34.1 ± 1.8 and 34.3 ± 1.7 min for SS and FF, respectively. These data indicate that short-term food options to initiate glycogen resynthesis can include dietary options not typically marketed as sports nutrition products such as fast food menu items.
John S. Cuddy, Dustin R. Slivka, Walter S. Hailes, Charles L. Dumke and Brent C. Ruby
The purpose of this study was to determine the metabolic profile during the 2006 Ironman World Championship in Kailua-Kona, Hawaii.
One recreational male triathlete completed the race in 10:40:16. Before the race, linear regression models were established from both laboratory and feld measures to estimate energy expenditure and substrate utilization. The subject was provided with an oral dose of 2H2 18O approximately 64 h before the race to calculate total energy expenditure (TEE) and water turnover with the doubly labeled water (DLW) technique. Body weight, blood sodium and hematocrit, and muscle glycogen (via muscle biopsy) were analyzed pre- and postrace.
The TEE from DLW and indirect calorimetry was similar: 37.3 MJ (8,926 kcal) and 37.8 MJ (9,029 kcal), respectively. Total body water turnover was 16.6 L, and body weight decreased 5.9 kg. Hematocrit increased from 46 to 51% PCV. Muscle glycogen decreased from 152 to 48 mmoL/kg wet weight pre- to postrace.
These data demonstrate the unique physiological demands of the Ironman World Championship and should be considered by athletes and coaches to prepare sufficient nutritional and hydration plans.
Charles L. Dumke, Christopher M. Pfaffenroth, Jeffrey M. McBride and Grant O. McCauley
In this study, a comparison was made between muscle strength, power and muscle and tendon (km and kt respectively) stiffness of the triceps surae muscle group and running economy (RE) in trained male runners.
Twelve well-trained male runners (age = 21 + 2.7 y, height = 178.1 ± 7.1 cm, body mass = 66.7 + 3.2 kg, VO2 max = 68.3 + 4.3 mLkg–1min–1, 5000-m time = 15:04 min:s) underwent passive stiffness testing using a free oscillation method. Muscle strength was determined via a maximal isometric squat test and power determined via a maximal countermovement jump (CMJ). On a separate day, subjects performed an incremental treadmill test and their RE, lactate threshold, and VO2 max were determined. Fingertip blood lactate was determined at the end of each 3-min stage. Lactate threshold was defined as a nonlinear increase in lactate accumulation.
A statistically significant correlation was found between k m and VO at stage 6 (r = -0.69, P = .01). In addition, statistically significant correlations were observed between CMJ peak force production and VO2 at stage 2 (r = .66, P = .02), stage 3 (r = .70, P = .01), and stage 4 (r = .58, P = .04). No other statistically significant correlations were observed.
These data suggest that greater muscle stiffness and less power are associated with greater RE. Future study in this area should focus on determining the mechanisms behind this relationship and how to best apply them to a running population through training techniques.
John Quindry, Lindsey Miller, Graham McGinnis, Brian Kliszczewiscz, Dustin Slivka, Charles Dumke, John Cuddy and Brent Ruby
Previous research findings indicate that environmental temperature can influence exercise-induced oxidative-stress responses, although the response to variable temperatures is unknown. The purpose of this study was to investigate the effect of warm, cold, and “neutral,” or room, environmental temperatures on the blood oxidative stress associated with exercise and recovery. Participants (N = 12, age 27 ± 5 yr, VO2max = 56.7 ± 5.8 ml · kg-1 · min-1, maximal cycle power output = 300 ± 39 W) completed 3 exercise sessions consisting of a 1-hr ride at 60% Wmax, at 40% relative humidity in warm (33 °C), cold (7 °C), and room-temperature environments (20 °C) in a randomized crossover fashion. Rectal core temperature was monitored continually as participants remained in the respective trial temperature throughout a 3-hr recovery. Blood was collected preexercise and immediately, 1 hr, and 3 hr postexercise and analyzed for oxidative-stress markers including ferric-reducing ability of plasma (FRAP), Trolox-equivalent antioxidant capacity (TEAC), lipid hydroperoxides, and protein carbonyls. Core temperature was significantly elevated by all exercise trials, but recovery core temperatures reflected the given environment. FRAP (p < .001), TEAC (p < .001), and lipid hydroperoxides (p < .001) were elevated after warm exercise while protein carbonyls were not altered (p > .05). These findings indicate that moderate-intensity exercise and associated recovery in a warm environment elicits a blood oxidative-stress response not observed at comparable exercise performed at lower temperatures.
John Quindry, Lindsey Miller, Graham McGinnis, Megan Irwin, Charles Dumke, Meir Magal, N. Travis Triplett, Jeffrey McBride and Zea Urbiztondo
Acute strength exercise elicits a transient oxidative stress, but the factors underlying the magnitude of this response remain unknown. The purpose of this investigation was to determine whether muscle-fiber type relates to the magnitude of blood oxidative stress after eccentric muscle activity. Eleven college-age men performed 3 sets of 50 eccentric knee-extensions. Blood samples taken pre-, post-, and 24, 48, 72, and 96 hr postexercise were assayed for comparison of muscle damage and oxidative-stress biomarkers including protein carbonyls (PCs). Vastus lateralis muscle biopsies were assayed for relative percentage of slow- and fast-twitch muscle fibers. There was a mixed fiber composition (Type I = 39.6% ± 4.5%, Type IIa = 35.7% ± 3.5%, Type IIx = 24.8% ± 3.8%; p = .366). PCs were elevated 24, 48, and 72 hr (p = .032) postexercise, with a peak response of 126% (p = .012) above baseline, whereas other oxidative-stress biomarkers were unchanged. There are correlations between Type II muscle-fiber type and postexercise PC. Further study is needed to understand the mechanisms responsible for the observed fast-twitch muscle-fiber oxidative-stress relationship.
John C. Quindry, Steven R. McAnulty, Matthew B. Hudson, Peter Hosick, Charles Dumke, Lisa S. McAnulty, Dru Henson, Jason D. Morrow and David Nieman
Previous research indicates that ultramarathon exercise can result in blood oxidative stress. The purpose of this investigation was to examine the efficacy of oral supplementation with quercetin, a naturally occurring compound with known antioxidant properties, as a potential countermeasure against blood oxidative stress during an ultramarathon competition. In double-blind fashion, 63 participants received either oral quercetin (250 mg, 4×/day; 1,000 mg/day total) or quercetin-free supplements 3 weeks before and during the 160-km Western States Endurance Run. Blood drawn before and immediately after (quercetin finishers n = 18, quercetin-free finishers n = 21) the event was analyzed for changes in blood redox status and oxidative damage. Results show that quercetin supplementation did not affect race performance. In response to the ultramarathon challenge, aqueous-phase antioxidant capacity (ferric-reducing ability of plasma) was similarly elevated in athletes in both quercetin and quercetin-free treatments and likely reflects significant increases in plasma urate levels. Alternatively, trolox-equivalent antioxidant capacity was not altered by exercise or quercetin. Accordingly, neither F2-isoprostances nor protein carbonyls were influenced by either exercise or quercetin supplementation. In the absence of postrace blood oxidative damage, these findings suggest that oral quercetin supplementation does not alter blood plasma lipid or aqueous-phase antioxidant capacity or oxidative damage during an ultramarathon challenge.
Graham McGinnis, Brian Kliszczewiscz, Matthew Barberio, Christopher Ballmann, Bridget Peters, Dustin Slivka, Charles Dumke, John Cuddy, Walter Hailes, Brent Ruby and John Quindry
Hypoxic exercise is characterized by workloads decrements. Because exercise and high altitude independently elicit redox perturbations, the study purpose was to examine hypoxic and normoxic steady-state exercise on blood oxidative stress. Active males (n = 11) completed graded cycle ergometry in normoxic (975 m) and hypoxic (3,000 m) simulated environments before programing subsequent matched intensity or workload steady-state trials. In a randomized counterbalanced crossover design, participants completed three 60-min exercise bouts to investigate the effects of hypoxia and exercise intensity on blood oxidative stress. Exercise conditions were paired as such; 60% normoxic VO2peak performed in a normoxic environment (normoxic intensity-normoxic environment, NI-NE), 60% hypoxic VO2peak performed in a normoxic environment (HI-NE), and 60% hypoxic VO2peak performed in a hypoxic environment (HI-HE). Blood plasma samples drawn pre (Pre), 0 (Post), 2 (2HR) and 4 (4HR) hr post exercise were analyzed for oxidative stress biomarkers including ferric reducing ability of plasma (FRAP), trolox equivalent antioxidant capacity (TEAC), lipid hydroperoxides (LOOH) and protein carbonyls (PCs). Repeated-measures ANOVA were performed, a priori significance of p ≤ .05. Oxygen saturation during the HI-HE trial was lower than NI-NE and HI-NE (p < .05). A Time × Trial interaction was present for LOOH (p = .013). In the HI-HE trial, LOOH were elevated for all time points post while PC (time; p = .001) decreased post exercise. As evidenced by the decrease in absolute workload during hypoxic VO2peak and LOOH increased during HI-HE versus normoxic exercise of equal absolute (HI-NE) and relative (NI-NE) intensities. Results suggest acute hypoxia elicits work decrements associated with post exercise oxidative stress.