COCOA-BASED PROTEIN AND CARBOHYDRATE DRINK DECREASES PERCEIVED SORENESS AFTER EXHAUSTIVE AEROBIC EXERCISE: A PRAGMATIC PRELIMINARY ANALYSIS NICOLE M. MCBRIER,1 GIAMPIETRO L. VAIRO,1 DEE BAGSHAW,2 JAIMY M. LEKAN,3 PETER L. BORDI,4 5 AND PENNY M. KRIS-ETHERTON 1
Department of Kinesiology, The Pennsylvania State University, University Park, Pennsylvania; 2The Full Yield, Incorporated, Boston, Massachusetts; 3Division of Health and Physical Education, Baldwin Wallace College, Berea, Ohio; 4School of Hotel Restaurant and Recreation Management, The Pennsylvania State University, University Park, Pennsylvania; and 5Department of Nutritional Sciences, The Pennsylvania State University, University Park, Pennsylvania
ABSTRACT McBrier, NM, Vairo, GL, Bagshaw, D, Lekan, JM, Bordi, PL, and Kris-Etherton, PM. Cocoa-based protein and carbohydrate drink decreases perceived soreness after exhaustive aerobic exercise: A pragmatic preliminary analysis. J Strength Cond Res 24(8): 2203–2210, 2010—The purpose of this pragmatic preliminary analysis was to examine the effectiveness of a cocoa-based protein and carbohydrate prototype drink on skeletal muscle damage and perceived soreness after exhaustive exercise. A repeated-measures experimental design was used. Common biomarkers indicative of skeletal muscle damage included creatine kinase (CK), urinary isoprostanes and inflammatory markers (IL-6, IL-8, C-Reactive Protein [CRP]). Self-reported perception of postexercise soreness was also evaluated. Seven men participated in an exercise session consisting of a 30-minute run on a declined treadmill (210% grade). Running speed was adjusted accordingly so that participants consistently maintained 75% maximal heart rate. Drinks were ingested immediately after exercise, 2 hours postexercise, and before bed. Blood draws were sampled 30, 60, 120, and 360 minutes postexercise; urine was collected 24 and 48 hours postexercise. A perceived soreness questionnaire was administered 24 and 48 hours postexercise. The test drink had no effect on IL-6, CK, IL-8, CRP, or urinary isoprostanes (p . 0.05). However, the drink decreased the change in perceived soreness from 24 to 48 hours (p = 0.03). Consuming the drink after exercise resulted in a mean change of 2.6 6 6 compared to 13.7 6 10 for the control. In summary, the drink was effective
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in decreasing the level of self-reported perceived soreness after exhaustive exercise.
KEY WORDS muscle damage, creatine kinase, DOMS INTRODUCTION
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elayed onset muscle soreness (DOMS) is a common response to exercise experienced among competitive athletes and recreational physically active persons alike. Classic signs of DOMS include tissue point tenderness, clinical stiffness, and often severe pain with movement that peaks within 24–48 hours postexercise (5). Numerous and various hypotheses exist regarding the mechanisms of DOMS, although the exact cause is still unknown. Contemporary exercise and sport science researchers propose that several factors are attributed to DOMS, including an excessive production of creatine kinase (CK) and inflammatory mediators yielded from the disruption of muscle fibers (5). Eccentric, or lengthening, contractions are the most damaging actions to skeletal muscle cell membranes and contractile proteins as a result of high force production (9). Damage to muscle cell structure elicits an inflammatory response, which increases free radical production (16). Exercise, especially aerobic in nature, at moderate to high intensity has been shown to increase free-radical production, in part because of the greater flux of oxygen within the cells and mitochondria (7). Laboratory protocols that use declined treadmill running to combine aerobic exercise with eccentric loading of the primary muscle movers successfully produce skeletal muscle cell damage in a controlled environment. For example, running at intensities ranging from 70–80% of maximal heart rate on a 16–17.5% downgrade, to simulate downhill exercise, has been found to elicit high levels of lower extremity muscle damage in moderately fit individuals (13,21). Furthermore, participants that are able to VOLUME 24 | NUMBER 8 | AUGUST 2010 |
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Cocoa Drink Decreases Perceived Soreness after Exercise tolerate this mode of high-intensity workload for 30–45 minutes, often report significantly elevated ratings of perceived muscle soreness in the days after such experimental exercise protocols (13). Postexercise DOMS is potentially related to heightened levels of biomarkers associated with skeletal muscle cell damage and oxidative stress (13,21). Consequently, there is evidence to support the beneficial effects of antioxidant dietary supplementation against muscle damage induced by exhaustive exercise (26). One particular antioxidant that is receiving considerable attention in contemporary clinical sports medicine is cocoa. Cocoabased drinks, consisting of dietary flavanols, have demonstrated capacity to lower plasma levels of F2-isoprostane, a measure of oxidative stress (27). Moreover, chocolate milk has also been observed to be an effective recovery aid after exercise. For instance, Karp et al. (12) observed similar increases in time to exhaustion and total work for individuals that consumed chocolate milk when compared to a traditional electrolyte replenishing drink subsequent to exhaustive exercise. These findings suggest that cocoa-based drinks may potentially serve as an effective recovery aid to exercise and physical activity. Exercise also has a profound impact on protein metabolism (3,8,14,22,23,25) that can last from minutes to days. One of the goals of successful physical training is to create, sustain, or improve equilibrium between synthesis and degradation of proteins and amino acids. Because protein metabolism is a dynamic process, changes in the nitrogen balance equation can be influenced through diet to cause an increase or decrease in protein synthesis or degradation independently or in combination of the 2 (21,23,26). A typical way athletes and active persons try to aid this process is through the use of dietary supplementation via postexercise protein drinks. Specifically, drinks with a 3:1 carbohydrate-to-protein ratio have been found to increase the anabolic effects of protein and decrease muscle degradation postexercise for improving recovery and performance subsequent to exercise (15,23,24). Although various experiments have been conducted to investigate the effect of antioxidant dietary supplementation
on biomarkers of skeletal muscle damage and oxidative stress, the results are often equivocal and difficult to compare because of considerable variations in sampled populations and exercise protocols (18). Moreover, the practical application of antioxidant supplementation research studies has been considerably limited because of an overwhelming failure for measuring and reporting functional indices of exercise-induced muscle damage such as soreness (18). Therefore, the purpose of this pragmatic experiment was twofold: first to investigate the overall effectiveness of a welldefined custom manufactured cocoa-based protein and carbohydrate prototype drink on skeletal muscle cell damage and inflammatory biomarkers and perceived soreness associated with exhaustive exercise and secondly to assess if drink consumption before exercise offered additive effects. We hypothesized that the cocoa-based protein and carbohydrate prototype drink would decrease skeletal muscle cell and inflammatory biomarkers and perceived soreness compared to water, a standard fluid often consumed during exercise bouts. We also hypothesized that consuming the test drink before exercise would elicit further reductions in oxidative stress markers and perceived soreness.
METHODS Experimental Approach to the Problem
This experiment represents a within-participant design. The within-participant design refers to the repeated measures on each participant where each participant served as his own control (Figure 1). The independent variables were the drink condition (test-drink after, water, test-drink before). The dependent variables of interest were the biomarkers of oxidative stress and subjective reported muscle soreness scores. For this investigation, each participant represented a block in a randomized complete block design as the treatment (drink condition) was administered to the participants in a random order. We employed a randomized complete block method because of its simplistic design and explanatory and pragmatic clinical applicability for this preliminary investigation while also serving to control and
Figure 1. Experimental design.
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Journal of Strength and Conditioning Research reduce experimental error. Each treatment (drink condition) was administered in a random order to every participant, for example (test-drink after ! water ! test-drink before). Such an approach models participants as random blocks in a randomized complete block method. This permits a mixed-model analysis of variance with random blocks (participants) and fixed treatment (drink condition) effects. The random allocation of treatments to blocks was restricted such that each drink condition occurred an equal number of times (once) within every participant. A random permutation of the order in which the treatments were administered to each block provides a random allocation of drink condition to every participant. There were 3! = 6 possible permutations of the 3 drink conditions. One permutation was randomly selected for each participant because a separate random permutation was required for all participants. A treatment label (test-drink after, water, test-drink before) was assigned a respective integer value (1–3), respectively. A random permutation of the integer values was obtained from a computer program (Minitab, State College PA, USA). Subjects
Seven physically active men were recruited for this research study. Physically active was defined as a person that is not sedentary but may not be in full compliance of the exercise guidelines set forth by Surgeon General, at least 30 minutes of moderate intense physical activity most days of the week. Our participants’ primary form of physical activity was anaerobic in nature. Participants filled out The Minnesota Leisure-time Physical Activity Questionnaire that monitored both a 7-day recall and a 1-year recall for activity (20). All participants read and signed a written informed consent approved by the Institutional Review Board. Participant demographics are presented in Table 1. Screening criteria were established to ensure that participants fell below the 70th percentile for aerobic capacity to minimize potential confounding antioxidant benefit as a result of heightened fitness level. Participants were excluded if they had a percent body fat greater than 25% as measured by a Dual Energy X-ray Absorptiometry (DEXA) scan, experienced a lower extremity injury within the previous 6 months and were currently taking chronic or daily doses of anti-inflammatory medication or other dietary supplements. Smokers, those
TABLE 1. Participant demographics (mean 6 SD). Age (y) Height (cm) Weight (kg) Percent body fat V_ O2max (mlkg21min21)
22.71 181.16 81.80 18.76 43.94
6 4.46 6 18.64 6 9.25 6 4.32 6 3.95
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experiencing chronic pain or muscle weakness, or those with lactose or soy intolerance were also excluded. Prototype Drink and Meals
A well-defined noncommercial cocoa-based protein and carbohydrate prototype drink was formulated with a ratio of 3.5:1 carbohydrate to protein. The drink was screened for microbiological quality both internally and externally. Each drink provided 330 ml that was equivalent to 220 cal. Nutrient content of the test drink is listed in Table 2. A standard breakfast and lunch were provided to all participants. Table 3 provides sample menus with portions and calories for both meals. In 2 cases, vegan meals were substituted, and efforts were made to ensure an approximate equivalent amount of calories. Dependent Variables
Blood markers (IL-6, IL-8, CK, and CRP) were drawn before exercise as a baseline, and at 30-, 60-, 120-, 360-minute intervals postexercise. Levels were determined via Enzyme linked immunosorbent assay (Northwest Life Science Specialties, LLC; kit: nwkiso02) at the University’s Core Endocrine Laboratory. Isoprostane (15-isoprostane F2t) were measured via urine samples taken in the morning at 24 and 48 hours after each exercise bout. Laboratory technicians were blinded as to which treatment condition the sample was from. The Lower Extremity Functional Scale (LEFS) was administered 24 and 48 hours postexercise to determine the participant’s level of difficulty with various physical activities. The LEFS is a validated 20-item questionnaire (R = 0.94) that asks participants to rate the perceived level of
TABLE 2. Cocoa drink nutrient content.* 1 Serving Calories Total fat Saturated fat Trans fat Cholesterol Sodium Total carbohydrates Dietary fiber Sugars Protein Vitamin A Vitamin C Calcium Iron Vitamin D Vitamin E Potassium Magnesium
330 mL 220 kcal 4g 0.5 g 0g 0 mg 430 mg 39 g 4g 25 g 11 g 10% DV 0% DV 10% DV 8% DV 10% DV 10% DV 10% DV 10% DV
*%Daily Value based on 2,000-cal diet.
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Cocoa Drink Decreases Perceived Soreness after Exercise
TABLE 3. Breakfast and lunch menus on day of testing. Breakfast Plain or wheat bagel (medium) Real butter, 2 tsp Bottled water Lunch Pretzels, 1 oz bag American Cheese (ca. 1 slice) Deli turkey Whole-wheat bread (ca. 2 slices) Yellow mustard (optional) 1 packet Soda, cola, or lemon lime, 8 oz can Bottled water Vegan meal plan Breakfast Plain or wheat bagel (medium) Margarine, Fleischmann’s, 2 tsp Bottled water Lunch Pretzels, 1 oz bag Peanut butter Jam Whole wheat bread (approx 2 slices) Yellow mustard (optional) 1 packet Soda, cola, or lemon lime, 8 oz can Bottled water
100 g
257 kcal
9.5 g 500 mL
68 kcal 0 kcal 352 kcal
28.4 g 37.8 g
108 kcal 124 kcal
52 g 64 g
57 kcal 158 kcal
3g
5 kcal
250 mL
100 kcal
500 mL
0 kcal 552 kcal
100 g
257 kcal
9.5 g
68 kcal
500 mL
0 kcal 352 kcal
28.4 g 21 g 24 g 64 g
108 kcal 123 kcal 67 kcal 158 kcal
3g
5 kcal
250 mL
100 kcal
500 mL
0 kcal 547 kcal
difficulty performing functional tasks on a 0–4 scale with 0 being unable to perform the activity and 4, having no difficulty at all (1). Procedures
Participants arrived at the General Clinical Research Center (GCRC) to review the informed consent and undergo an initial health screening including a standard blood screen, a coronary risk profile and resting electrocardiogram (ECG). The services provided by the GCRC were supported by National Institutes of Health (NIH) Grant M01 RR 10732. Participants with risk factors for coronary heart disease or an abnormal resting ECG indicating that exhaustive exercise
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would not be warranted were excluded. Participants cleared to proceed returned within 48 hours to have a physical examination, a DEXA scan and a V_ O2max test using a standard Bruce Protocol. This latter prescreen insured that participants qualified for inclusion based on level of fitness; below the 70th percentile for V_ O2max based on age. After testing, participants met with a registered dietician to discuss any diet modifications required for the study and were instructed to complete a 3-day diet record to assess food consumption and compliance with diet modifications. Four days before the exercise session, participants restricted their diets to be low in antioxidants and recorded what they ate for 3 of the 4 days. Participants submitted their diet records before each of the exercise testing sessions. A summary of dietary intake for participants is included in Table 4. Our participants demonstrated a significant reduction in antioxidants compared to a typical American diet that would be rich in antioxidant food. On the day of testing, participants arrived at the GCRC to have a fasted blood draw and received a standard breakfast low in antioxidants and protein (Table 3). Within 30 minutes, a topical analgesic (LMX cream, 4% lidocaine, Eloquest Healthcare, Ferndale, MI, USA) was applied to the anticubital vein area and covered with an occlusive dressing before beginning the exercise protocol. A heart rate monitor (Polar Electro Inc., Lake Success, NY, USA) was applied to the participant and used throughout the exercise session. The exercise session began with a 5-minute warm-up at 0% grade at 50% of their maximal heart rate; the treadmill was then declined to 210%, and speed was adjusted to elicit 75% of the participant’s maximal heart rate. This intensity was maintained for 30 minutes, with heart rate and perceived exertion assessed every 5 minutes. Adjustments in speed were periodically made to maintain relative intensity at 75% maximal heart rate. Participants then underwent a 5-minute cooldown period at 0% grade after which they were given a beverage to drink. At 20 minutes after exercise, a catheter was inserted in the anticubital vein to collect the first 3 blood draws (taken postexercise at 30, 60, 120 minutes). Water was given to subjects as needed but did not exceed 24 oz throughout the entire testing session (360 minutes). After the 120-minute blood draw, subjects received a second drink. Blood was spun 30 minutes after each consecutive draw and stored at 280°C until analysis. Following the 360-minute blood draw, subjects were also given a prepackaged meal. After the 360-minute blood draw, subjects were given a third beverage to take home and drink before bed. The following mornings (24 and 48 hours postexercise), they were asked to complete the LEFS questionnaire that assessed their perceived soreness and level of function. At 24 and 48 hours postexercise, subjects were also asked to submit a urine sample that was analyzed via a Diascreen 10 dipstick test (Hypoguard USA, Inc., Minneapolis, MN, USA) to monitor renal function. Any abnormal tests were to be referred to a clinician at the GCRC; none were noted during this study. This entire process was
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TABLE 4. Summary of dietary intake for participants before test days.
Nutrients
Participants’ diet
Calories Protein (g) Fat (g) Carbohydrate (g) Vit A (RE) (mg) B-carotene (mg) Vit E (IU) Vit C (mg) Lycopene (mg) Lutein + zeaxanthin (mg) Selenium (mg)
2,089 115.4† 73.2 241.7 589 595 8 25.1 1,237 736 181.4
% Macro
An American diet rich in antioxidants (ADAO)*
22.1† 31.6 46.3
2,700 92.2 104.1 380.2 4,501 25,574 25 374 22,176 10,111 59.9
% Macro 13.7 34.7 56.3
Recommended dietary allowance 3,067 56 ‡ 130 minimum 900 ‡ 15 90 ‡ ‡ 55
% Participants’ diet compared to ADAO
13.1 2.3 32.0 6.7 5.6 7.3 302.8§
*Dietary reference intakes. In: The Essential Guide to Nutrient Requirements. Otten, JJ, Hellwig, JP, Meyers, LD, eds. Washington, DC: Institute of Medicine of the National Academies, the National Academies Press, 2006, p. 70. †Grams and % protein higher than average American diet because of increase in meat intake secondary to low antioxidant choices. ‡No recommended dietary allowance established. §Meat and grains in study diet contribute to high selenium content.
repeated after 21 days alternating the type of drink condition (Figure 1). Statistical Analyses
A repeated-measures analysis of variance (ANOVA) was employed with each biomarker examined in this research study. Specifically, a 3 3 5 (drink condition 3 blood draw time) mixed model factorial treatment design was used where drink condition and blood draw time served as fixed factors and participants served as a random factor. A 3 3 2 (drink condition 3 days postexercise) factorial ANOVA was performed to compare isoprostane levels in urine. Change scores for subjective measures of muscle soreness were compared across all 3 drink conditions using a univariate ANOVA. Post hoc analyses were performed when indicated for each dependent variable of interest using Fisher’s least significant difference. Statistical significance (alpha level) was set at p # 0.05 a priori.
RESULTS Drink condition was not a significant factor for measures of IL-8 (p = 0.965), IL-6 (p = 0.518), CRP (p = 0.741), and CK (p = 0.772). Time was also not a significant factor between IL-8 (p = 0.056) and CRP (p = 0.060). Furthermore, no significant drink condition–time interaction was found among IL-8 (p = 0.288), IL-6 (p = 0.937), CRP (p = 0.868), and CK (p = 0.975). A significant time effect was observed for IL-6 (p = 0.004) and CK (p = 0.028). Post hoc testing revealed that levels of IL-6 and CK measured at 360 minutes postexercise were significantly greater than all
other blood draw time intervals measured throughout the experiment. There was no significant difference observed for the level of isoprostanes in urine at 24 or 48 hours postexercise (p = 0.332) across the drink conditions (p = 0.173). Drink condition significantly influenced change scores observed between 24 and 48 hours postexercise (p = 0.033). Post hoc testing revealed a significantly lower change score when the cocoa beverage was administered after exercise (p = 0.010). There was no difference observed when the test drink was administered before exercise (p = 0.138). Consuming the test drink after exercise resulted in a mean change of 2.6 6 6 compared to 13.7 6 10 for the control.
DISCUSSION Although skeletal muscle tissue possesses considerable adaptive traits, responses to the stresses of exercise and physical training may not be optimally regulated solely by the body (18). Therefore, many physically active persons, especially athletes, routinely employ dietary supplementation regimens as a component of their exercise routines and healthy lifestyle. As a result of this trend, a considerable proportion of the exercise science and sports nutrition literature has focused on investigating the effectiveness and efficaciousness of dietary supplementation on human physiology and performance. Even with the vast amount of literature, the results and interpretations are still under increasing scrutiny because of inconsistencies in research methods and varying results. Differences among fitness VOLUME 24 | NUMBER 8 | AUGUST 2010 |
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Cocoa Drink Decreases Perceived Soreness after Exercise levels, gender respective responses to stresses (4,10), the type and timing of the supplement administered (2,6) and subjective measurements of soreness and function (1) impact results. Therefore, we implemented strict experimental methods, especially regarding subject inclusion and exclusion criteria, in our investigation with the purpose of standardizing the protocol to permit ideal laboratory techniques in a practical scenario. We observed increases in CK enzyme level, IL-6 level, and perceived muscle soreness after our exercise protocol. The increases in these variables demonstrate that the downhill running protocol used in this study was effective in generating skeletal muscle damage and in turn the perceived soreness. Interestingly, these specific findings contrast those of prior similar experiments that assessed muscle damage, soreness and the effects of antioxidant and protein dietary supplementation after a bout of downhill running (10,13,21). A potential factor responsible for the differences between our exercise response and those of prior investigators may stem from the employed experimental methods. For instance, Green et al. (10) did not observe a difference in CK among treatment conditions (carbohydrate drink, carbohydrate: protein drink, placebo) in their participants. Creatine kinase is a consistent biomarker used to measure skeletal muscle cell damage because increased levels of this enzyme in the blood indicates disruption of the z-line in the sarcolemma (5). The lack of a measurable difference of this biomarker in his subjects is potentially because the exercise protocol used, which consisted of a fixed speed (8 mph) for all participants as opposed to individualized speed (75% of maximal heart rate) used in our experiment. Therefore, it may be possible that the protocol of Green et al. (10) did not impose adequate skeletal muscle cell damage to induce substantial perceived postexercise muscle soreness in participants. The mode for evaluating subjective rating of perceived muscle soreness after a bout of exercise further highlights a notable feature of our experiment. For example, our investigation represents an innovative approach to assessing a specific functional index of exercise induced muscle damage via the LEFS as opposed to the more traditional visual analog scale (VAS), which is often employed to monitor general muscle soreness. One of the benefits of using the LEFS as opposed to a traditional VAS is that the LEFS examines multiple activities associated with daily living in 1 questionnaire (1). Some of the challenges associated with using the VAS are when, how often and in what manner to administer it. The VAS is a nonspecific measurement of pain and may underestimate levels of pain or soreness especially if it is administered in the traditional manner, with the person seated and comfortable. Kaminski and Boal (11) addressed this concern by administering the VAS in 4 ways: at rest, during self-palpation, during stretch and exercise to examine the effect of antioxidant supplementation on perceived muscle soreness after a bout of anaerobic exercise. Their goal was to maximize the use of the VAS by having it
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completed with different activities similar to the LEFS. They demonstrated a decrease in perceived soreness in the group supplemented with Vitamin C (25–32% reduction). This decrease is probably more evident because of the nature of administration of the VAS. Similarly, in our study, the LEFS provided an initial, although basic, assessment into functional muscle soreness by assessing soreness associated with activities as opposed to overall soreness that is perceived postexercise. The LEFS differs from VAS in that it asks individuals to rate their pain or soreness after specific functional based activities. DOMS gradually increases 24 hours postexercise and typically peaks 48 hours postexercise before beginning to decline (16). As such, we purposely examined the change in perceived muscle soreness at 24 and 48 hours postexercise to determine the effect of the drink intervention. For those trials where the test drink was ingested after exercise we noted significantly less of a reported change from 24 to 48 hours by the participants. This indicated a decrease in perceived DOMS and therefore less difficulty in performing various physical tasks 48 hours postexercise. Ingesting drinks immediately after the exercise bouts has been previously shown to have positive effects on the body (25). We did not observe a significant difference when the drink was ingested before the exercise bout. It is possible that by ingesting the drink before exercise, it was used more as a readily available energy substrate than as a recovery aid. Therefore, it served no additional benefit because appropriate calories were provided to each subject across condition before the running protocol. Previous research has suggested cocoa-based beverages, such as chocolate milk, exhibit benefits as a postexercise recovery drinks (12,21,28). These benefits include decreases in oxidative stress markers (28) and muscle soreness (12) and increases in performance output (21). Unlike the findings of Wiswedel et al. (28), we did not find a drink influence on circulatory biomarkers or urinary isoprostanes indicative of skeletal muscle damage and oxidative stress commonly associated with exhaustive exercise. Instead our results parallel the observations of Mathur et al. (17) in that cocoa-based product dietary supplementation did not alter biomarkers of oxidative stress or inflammation. Nonetheless, it may be this combination of carbohydrates, protein and cocoa that has led to the difference in postexercise perceived muscle soreness observed in our study. An important distinction of the prototype drink in our research study, compared to other chocolate based drinks (i.e., chocolate milk), was that it was made primarily with natural cocoa, which possesses greater antioxidant capacity than Dutched cocoa. When cocoa is Dutched, or treated with an alkaline solution, the solubility is improved allowing it to be blended more readily into a beverage. Consequently, the Dutching process reduces the antioxidant (flavanol) levels of cocoa (19). Wiswedel et al. (28) examined the influence of low and high levels of flavanols in cocoa beverages and observed a greater decrease in plasma F2-isoprostane (oxidative stress
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of this prototype and similar engineered recovery drinks in women, and adolescent boys and girls.
PRACTICAL APPLICATIONS Based on the findings of our experiment we conclude that a recovery drink composed of a carbohydrate-to-protein ratio of 3.5:1 with the addition of flavonol-rich cocoa may decrease perceived muscle soreness after exercise. The extent and duration to which an individual perceives muscle soreness after a training bout may be a considerable limiting factor for expediting the physical accommodation to exhaustive exercise and the development and refinement of physiological responses to exercise. By immediately consuming a cocoabased protein and carbohydrate recovery drink postexercise, the perception of muscle soreness may be minimized, allowing for an expedited recovery between training bouts. With such a decrease in perceived muscle soreness, athletes and physically active persons may be more likely to adhere to their training program, especially during periods of strenuous high volume physical activity. A benefit such as this may thereby considerably facilitate a consistent frequency of training sessions. Although we present evidence for the effectiveness of this prototype drink, additional study is necessary to determine the efficaciousness of cocoa supplementation for decreasing indices of oxidative stress and biomarkers and functional indices of exercise induced muscle damage, particularly among diverse populations. We also stress that further work must be conducted to establish the potential role of cocoa-based supplements in serving as an ergogenic aid.
ACKNOWLEDGMENTS We would like to thank The Hershey Company for funding this project. In addition we would like to thank Javier Osorio, Rick Ball, and the entire staff at the GCRC for all their help with this study.
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