1550-2783-5-8 1550-2783 Research article <p>Effects of acute and 14-day coenzyme Q10 supplementation on exercise performance in both trained and untrained individuals</p> Cooke Matthew matt_cooke@baylor.edu Iosia Mike miosia@leeuniversity.edu Buford Thomas thomas_buford@baylor.edu Shelmadine Brian brian_shelmadine@baylor.edu Hudson Geoffrey geoffrey_Hudson@baylor.edu Kerksick Chad chad_kerksick@ou.edu Rasmussen Christopher chris_rasmussen@baylor.edu Greenwood Mike mike_greenwood@baylor.edu Leutholtz Brian brian_leutholtz@baylor.edu Willoughby Darryn darryn_willoughby@baylor.edu Kreider Richard richard_kreider@baylor.edu

Exercise & Sport Nutrition Lab; Center for Exercise, Nutrition and Preventive Health; Department of Health, Human Performance & Recreation; Baylor University; Waco, TX, USA

Department of Health, Exercise Science, and Secondary Education; Lee University; Cleveland, TN, USA

Department of Health and Exercise Science; University of Oklahoma; Norman, OK, USA

 Journal of the International Society of Sports Nutrition 1550-2783 2008 5 1 8 http://www.jissn.com/content/5/1/8 18318910 10.1186/1550-2783-5-8 11 1 2008 04 3 2008 04 3 2008 2008 Cooke et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Background

To determine whether acute (single dose) and/or chronic (14-days) supplementation of CoQ10 will improve anaerobic and/or aerobic exercise performance by increasing plasma and muscle CoQ10 concentrations within trained and untrained individuals.

Methods

Twenty-two aerobically trained and nineteen untrained male and female subjects (26.1 ± 7.6 yrs, 172 ± 8.7 cm, 73.5 ± 17 kg, and 21.2 ± 7.0%) were randomized to ingest in a double-blind manner either 100 mg of a dextrose placebo (CON) or a fast-melt CoQ10 supplement (CoQ10) twice a day for 14-days. On the first day of supplementation, subjects donated fasting blood samples and a muscle biopsy. Subjects were then given 200 mg of the placebo or the CoQ10 supplement. Sixty minutes following supplement ingestion, subjects completed an isokinetic knee extension endurance test, a 30-second wingate anaerobic capacity test, and a maximal cardiopulmonary graded exercise test interspersed with 30-minutes of recovery. Additional blood samples were taken immediately following each exercise test and a second muscle biopsy sample was taken following the final exercise test. Subjects consumed twice daily (morning and night), 100 mg of either supplement for a period of 14-days, and then returned to the lab to complete the same battery of tests. Data was analyzed using repeated measures ANOVA with an alpha of 0.05.

Results

Plasma CoQ10 levels were significantly increased following 2 weeks of CoQ10 supplementation (p < 0.001); while a trend for higher muscle CoQ10 levels was observed after acute CoQ10 ingestion (p = 0.098). A trend for lower serum superoxide dismutase (SOD) was observed following acute supplementation with CoQ10 (p = 0.06), whereas serum malondialdehyde (MDA) tended to be significantly higher (p < 0.05). Following acute ingestion of CoQ10, plasma CoQ10 levels were significantly correlated to muscle CoQ10 levels; maximal oxygen consumption; and treadmill time to exhaustion. A trend for increased time to exhaustion was observed following 2 weeks of CoQ10 supplementation (p = 0.06).

Conclusion

Acute supplementation with CoQ10 resulted in higher muscle CoQ10 concentration, lower serum SOD oxidative stress, and higher MDA levels during and following exercise. Chronic CoQ10 supplementation increased plasma CoQ10 concentrations and tended to increase time to exhaustion. Results indicate that acute and chronic supplementation of CoQ10 may affect acute and/or chronic responses to various types of exercise.

Background

In recent years, Coenzyme Q10 (CoQ10) has gained considerable attention as a dietary supplement capable of influencing cellular bioenergetics and counteracting some of the damage caused by free radicals 1234. CoQ10 is a vitamin like, fat-soluble substance existing in all cells 5. It is intimately involved in several important roles in the body including the transferring of electrons within the mitochondrial oxidative respiratory chain and hence, ATP production; acting as an essential antioxidant and supporting the regeneration of other antioxidants; influencing the stability, fluidity and permeability of membranes; and, stimulating cell growth and inhibiting cell death 567.

In clinical populations, CoQ10 has been used as a supplementary treatment for chronic diseases such as Chronic Heart Failure (CHF), muscular dystrophies, Parkinson's disease, cancer, and diabetes 89. In CHF patients, a disease characterized by lower than normal CoQ10 levels, CoQ10 supplementation has shown to improve stroke volume, ejection fraction and exercise capacity in several double-blind, placebo-controlled studies 4. In athletes, CoQ10 deficiency may also be experienced as metabolic stress and free radical formation is elevated during times of intense training 71011. Thus, given our current understanding into the functions of CoQ10 within the body, it has been hypothesized that dietary supplementation with CoQ10 may not only be beneficial to clinical patients, but also healthy active individuals who may potentially experience CoQ10 deficiency 3.

While this theory is plausible, results of studies that have evaluated the potential ergogenic value of CoQ10 in athletes have reported mixed results 4. For example, several studies have found that CoQ10 supplementation (60–100 mg/day for 4–8 weeks) improves aerobic power, anaerobic threshold, exercise performance, and/or recovery after exercise in trained athletes and untrained individuals 121314. Conversely, other studies using similar dosages (60–150 mg/day for 3–8 weeks) have found no ergogenic benefit on maximal or submaximal exercise capacity in untrained and trained individuals 1516171819.

One possible explanation for these inconsistent findings is that the absorption of CoQ10 into the mitochondrial membrane or non-deficit tissues is rather inefficient. In this regard, CoQ10 is a relatively large, hydrophobic molecule 20. Therefore, absorption of CoQ10 into tissues is often slow and limited. Formulations that could maximize CoQ10 absorption would not only improve its uptake into the plasma, but potentially improve its absorption into the skeletal muscle. Recently, the bioavailability and absorptive properties of several CoQ10 preparations were examined (i.e., fast-melt tablet, effervescent tablet, soft gelatin liquid capsule, and a hard shell powdered capsule) 21. Results indicated that the fast-melt tablet and effervescent formulation provided a more rapid delivery of CoQ10 to the blood, while exhibiting similar pharmacokinetic properties compared with the soft gel and hard capsule forms of CoQ10 21. These findings suggest that provision of CoQ10 in a fast-melt or effervescent form may facilitate CoQ10 delivery and uptake to the muscle. Theoretically, this may enhance bioavailability of CoQ10 and promote a greater metabolic and/or ergogenic impact. However, the effects of acute and chronic ingestion of a fast-melt form of CoQ10 on muscle CoQ10 concentrations and exercise performance is unknown. Therefore, the purpose of this study was to determine whether acute (single-dose) and chronic (14-days) supplementation with a fast-melt form of CoQ10 will affect muscle CoQ10 concentrations, improve anaerobic and aerobic performance, and/or affect markers of oxidative stress in trained and untrained individuals.

Methods

Subjects

Twenty-two aerobically trained and nineteen untrained male and female subjects (26.1 ± 7.6 yrs, 172 ± 8.7 cm, 73.5 ± 17 kg, and 21.2 ± 7.0%) participated in this study. Aerobically trained individuals had been training a minimum of two years for an average of 8 ± 2 hours/week, 9 ± 3 workouts/week, and averaged 68 ± 36 kilometers/week of aerobic exercise (i.e., running, cycling and/or swimming). Untrained individuals did not participate in any regular form of aerobic exercise for at least the past year.

All subjects signed informed consent documents and the study was approved by the Baylor University Institutional Review Board prior to any data collection. Subjects were not allowed to participate in this study if they reported any of the following: 1) current or past history of anabolic steroid use; 2) any metabolic disorders or taking any thyroid, hyperlipidmeic, hypoglycemic, anti-hypertensive, or androgenic medications; 3) ingested any ergogenic levels of creatine, HMB, thermogenics, ribose, pro-hormones (i.e., DHEA, androstendione, etc.) or other purported anabolic or ergogenic nutritional supplements within 2 months prior to beginning the study and to not take any additional nutritional supplement or contraindicated prescription medication during the protocol.

Experimental design

Figure 1 shows the experimental design used in this study. The study was conducted in a randomized, double-blinded, and placebo-controlled manner. All subjects eligible to participate in the study completed a familiarization session where they were provided information (both verbal and written) regarding the study design, testing and supplementation protocols. Informed consent, medical documents and training history questionnaires were also completed at this time. Subjects were then required to perform an isokinetic leg extension test and 30-second anaerobic Wingate test to become familiar with the protocol and equipment. The procedures for all exercise tests are described in detail below. Following the practice trials, subjects were scheduled to return 48 hours later for baseline testing. Subjects were asked to not change their dietary habits in any way throughout the study. This was monitored by having each subject document dietary intake for 4 days (3 weekdays and 1 weekend day) before each testing session. In addition, each subject was instructed to fast for 12 hours and not to perform any physical activity for the 48 hours preceding each testing session.

<p>Figure 1</p>

Schematic diagram of research design

Schematic diagram of research design.

At baseline testing (T1), subjects reported to the lab in the morning to complete questionnaires regarding health status. Subjects then performed three exercise tests in the following order: 1.) isokinetic knee extension muscle endurance test; 2.) 30-second Wingate anaerobic capacity test; and, 3.) a maximal cardiopulmonary graded exercise test. Thirty minute rest periods were allocated between each exercise test. Following baseline measurements, subjects were matched based on age and aerobic capacity and randomly separated into two groups: 1.) a dextrose placebo group; or 2.) a fast-melt CoQ10 group [Fast-Melt Coenzyme Q10, Pharma Base, S.A. (Switzerland)]. Subjects were instructed to return to the lab in 48 hours for testing and ingestion of the first supplement.

On returning to the lab (Day 0, T2), subjects completed the questionnaires. Prior to ingestion of the first supplement dose, body mass, total body water, and body composition measurements were obtained. Subjects then donated approximately 20 ml of fasting blood and approximately 15–30 mg of muscle using standard procedures described below. Subjects consumed either the placebo or CoQ10 supplement. At 60 minutes following ingestion of the supplement, subjects performed the three exercise tests as mentioned above with 30 minutes of recovery between each exercise test. Additional blood samples were taken immediately following each exercise test. Subjects returned to the lab following 2 weeks of supplementation to complete the same battery of assessments. No supplement was ingested on day 14 (T3) prior to performing the exercise tests.

Exercise protocol

Muscle endurance assessment

At baseline, day 0 and 14, subjects performed a 50-repetition Isokinetic leg extension test. Prior to testing, subjects warmed up on a stationary bicycle for 2–3 min at a 50–60 rpm. Subjects then performed five warm-up repetitions on the Biodex (Biodex Medical Systems, Shirley, NY, USA) isokinetic leg extension machine. After these warm-up repetitions, subjects performed unilateral leg extensions (right leg) for one set of 50 repetitions 22 at 180 degrees/s. Test-test reliability of this test has been shown to be 0.78 to 0.82 23.

Anaerobic capacity assessment

At baseline, day 0, and day 14, subjects performed a 30-second Wingate anaerobic capacity test 30 minutes following completion of the muscle endurance test. Subjects warmed up for 2 min at 50–60 rpm on a stationary bicycle ergometer before performing the Wingate test. This warm-up was continued into the start of the sprinting portion of the Wingate test, which allows for a flying start. The Wingate anaerobic capacity test was performed on the LODE cycle ergometer (Amsterdam, Netherlands) with a resistance of 0.7 Nm/kg. Test-to-test variability in performing repeated Wingate tests in our laboratory yielded correlation coefficients of r = 0.98 ± 15% for mean power.

Cardiopulmonary assessment

At baseline, day 0, and 14, subjects performed a volitional maximal cardiopulmonary exercise test according to the Bruce protocol 30 minutes following the anaerobic capacity test 24. Participants were instructed to perform the test for as long as possible to ensure a true maximal attempt. Standard ACSM test termination criteria were monitored and followed throughout each test 25. Metabolic gases were obtained with the Parvo Medics 2400 TrueMax metabolic measurement system (Sandy, UT, USA) on a Trackmaster TMX425C treadmill (Newton, KS, USA). The mean coefficient of variation (assessing maximum oxygen consumption) for this protocol was 6.5% (range, 2–14%) 24. Ventilatory threshold (VANT) was expressed as a percentage maximal oxygen consumption (mL·kg-1·min-1). To determine VANT, data from the graded exercise test for minute ventilation (VE), ventilation equivalent of VO2 (VE/VO2), and ventilation equivalent of VCO2 (VE/VO2) were plotted against exercise time (i.e. workload) and analyzed manually by an experienced exercise physiologist in a blinded manner.

Supplementation protocol

Subjects were assigned in a double-blind and randomized manner to ingest a dextrose placebo (CON, n = 20) or fast-melt CoQ10 formulation (CoQ10, n = 21). Subjects were matched into one of two groups according to age and aerobic capacity. Subjects were required to initially ingest 2 capsules (100 mg) prior to exercise performance testing on day 0. Following testing on day 0, subjects continued consuming 100 mg twice daily (morning and night) for 14 days. Supplements were prepared in tablet form and packaged in generic bottles for double blind administration by Pharma Base, S.A. (Switzerland). Supplementation compliance was monitored by having the subjects return empty bottles of the supplement at the end of 14 days of supplementation.

Procedures

Dietary inventories

Prior to each testing session, subjects were instructed to record all food and fluid intake over a 4-day period, which was reflective of their normal dietary intake and to include one weekend day. Dietary inventories were then reviewed by a registered dietician and analyzed for average energy and macronutrient intake using the ESHA Food Processor (Version 8.6) Nutritional Analysis software (Salem, OR, USA).

Anthropometrics

At the beginning of every testing session, subjects had their height and body mass measured according to standard procedures using a Healthometer (Bridgeview, IL, USA) self-calibrating digital scale with an accuracy of ± 0.02 kg.

Body composition

Total body water was estimated using a Xitron 4200 Bioelectrical Impedance Analyzer (San Diego, CA). Whole-body composition measurements (excluding cranium) were determined with a Hologic Discovery W Dual-Energy X-ray Absorptiometer (DEXA; Hologic, Bedford, MA, USA) by using procedures previously described 2627. Test-retest reliability studies performed on male athletes with this DEXA machine revealed mean deviation for total bone mineral content and total fat free/soft tissue mass of 0.31% with a mean intraclass correlation of 0.985.

Blood collection

Subjects were required to fast for 12 hrs prior to donating approximately four teaspoons (20 milliliters) of venous blood from an antecubital vein using standard phlebotomy procedures. Blood analyzed for CoQ10 was placed in a test tube containing heparin as the anticoagulant and immediately centrifuged at 3000 g using a standard bench top centrifuge (Cole Palmer, Vernon Hills, IL, Model # 17250-10) for 15 minutes at room temperature. Plasma was separated and stored at -80°C in polypropylene tubes for later analysis. Blood analyzed for makers of oxidative stress and clinical chemistry panels were placed into two serum separation tubes and immediately centrifuged at 1100 g for 15 min. Serum was separated and stored at -80°C in polypropylene tubes for later analysis. Finally, blood was collected in a single lavender top tube containing K2 EDTA and refrigerated for approx 4–6 h for subsequent complete blood count with platelet differentials analysis (hemoglobin, hematocrit, red blood cell counts, MCV, MCH, MCHC, RDW, white blood cell counts, neutrophils, lymphocytes, monocytes, eosinophils, baosphils) using an Abbott Cell Dyn 3500 (Abbott Laboratories, Abbott Park, IL) automated hematology analyzer. Whole blood was only analyzed pre- and post-exercise.

Clinical chemistry analysis

Serum samples were analyzed using a Dade Behring Dimension RXL (Deerfield, IL, USA) automated clinical chemistry analyzer that was calibrated and optimized according to manufacturer guidelines. This analyzer has been known to be highly valid and reliable in previously published reports 28. Each serum sample was assayed for a standard complete metabolic panel [(glucose, aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), albumin, globulin, sodium, chloride, calcium, carbon dioxide, total bilirubin)], lipid panel [(triglycerides, total cholesterol, high-density lipoprotein (HDL), low-density lipoprotein (LDL), total cholesterol:HDL)] and clinical markers of protein and fatty acid metabolism [(uric acid, creatinine, blood urea nitrogen (BUN), BUN:creatinine ratio, total protein, creatine kinase (CK), ketones (betahydroxybutyrate), and lactate dehydrogenase (LDH)]. Test to test reliability (within and between) of performing these assays ranged from 2 to 6% for individual assays with an average CV of ± 3%. Samples were run in duplicate to verify results if the observed values were outside control values and/or clinical norms according to standard procedures.

Markers of oxidative stress

Serum samples were assayed using standard commercially available spectrophotometric assay kits (Caymen Chemical Company, Michigan, USA) for Thiobarbituric Acid Reactive Substance (TBARS, Malondialdehyde-MDA) and Superoxide Dismutase (SOD). Enzyme immunoassay (EIA) was used to measure serum 8-Isoprostane. Serum concentrations were determined using a Wallac-Victor IV (Perkin-Elmer Life Sciences, Boston, MA) micro plate reader at an optical density of 450 nm against a known standard curve using standard procedures. Test to test reliability (within and between) of performing these assays ranged from 3 to 6% for individual assays with an average CV of ± 4%.

Muscle sample collection

Fine Needle Aspiration (FNA) muscle biopsies were taken on days 0 and 14 prior to, and following performance tests in order to examine total CoQ10 content in the muscle according to standard procedures 29. Participants were instructed to refrain from exercise 48 h prior to each muscle biopsy. Muscle was extracted from the lateral portion of the vastus lateralis midway between the patella and iliac crest of the dominant leg using a TRU-CORE® 1 Automatic Reusable Biopsy Instrument (Angiotech, Medical Device Technologies, INC., Gainsville, Florida, USA). Briefly, 0.5 ml of 1.0% Lidocaine HCl was injected subcutaneously prior to making a small pilot hole with a 23 gauge sterile needle. The biopsy needle was placed into the biopsy device and the inserted into the previously made pilot hole (a depth of about 5–10 mm). A muscle sample was obtained by the activation of a trigger button, which unloaded the spring and activated the needle to collect a muscle piece. The biopsy needle was removed from the pilot hole and the muscle specimen was removed from the biopsy needle using a sterile scalpel and immediately frozen in liquid nitrogen and stored at -80°C for further analyses. This whole biopsy procedure was repeated two to three times in order to obtain sufficient muscle tissue (15–30 mg).

CoQ10 determination

Frozen plasma and muscle samples were sent to Craft Technologies (Wilson, NC, USA) for assay of plasma and muscle CoQ10 concentrations using methods described by Tang et al., 29 and Rousseau and Varin 30. Total CoQ10 was determined by summing the oxidized and reduced forms.

Statistical analysis

Data are presented in all tables and throughout the text as mean (± SD). Plasma and muscle CoQ10 levels and markers of oxidative stress were analyzed using 2 × 2 × 2 × 4 (group × training status × gender × exercise [Baseline, Isokinetic, Wingate, Cardiopulmonary]) repeated measures ANOVA to assess the changes in plasma and muscle CoQ10 levels and markers of oxidative stress following acute (T2) and chronic (T3) supplementation. Delta scores (post minus pre values) were calculated for each exercise test (Isokinetic, Wingate, Cardiopulmonary) and analyzed using repeated measures ANOVA. All remaining data were analyzed using 2 × 2 × 2 × 3 (group × training status × gender × day [baseline, day 0 and 14]) repeated measures ANOVA. LSD pairwise comparisons were used to analyze any significant group × time interaction effects. Pearson product correlations were used to determine any relationship between criterion variables and an alpha level of 0.05 was adopted throughout to prevent any Type I statistical errors.

Results

Subject characteristics

There were no baseline differences in the age, body weight or height between the two groups (see Table 1).

<p>Table 1</p>

Subject Baseline Characteristics

Variable

CoQ10

Placebo

Age (yr)

25.76 ± 7.67

25.61 ± 8.07

Body Weight (kg)

76.02 ± 18.71

71.94 ± 18.12

Height (cm)

173.48 ± 7.42

168.18 ± 26.48

Data are means and ± standard deviations of mean

Side effects

No adverse events were reported concerning the supplementation or study protocol. No reports of medical problems or side effects were indicated in post-study questionnaires administered in a blinded manner.

Clinical safety markers

Complete blood counts with platelet differentials were run on all whole blood samples and a standard clinical safety panels was completed on all serum samples at baseline, day 0 and day 14. While some hematological variables did report main effects over time, no significant group × time interaction effects were observed and none of these changes occurred outside of the clinically accepted normative values for these variables 31. Therefore, these data are not reported. No significant main or group × time interaction effects (p < 0.05) were found for kidney/liver enzymes [e.g., GGT (p = 0.51), AST (p = 0.14), ALT (p = 0.43), ALP (p = 0.27)] or markers of protein breakdown [e.g., uric acid (p = 0.38), billirubin (p = 0.82), creatinine (p = 0.73), BUN:creatinine ratio (p = 0.80), total protein (p = 0.30), CK (p = 0.87)].

Lipid panels

Table 2 presents fasting lipid profile data observed throughout the study. No significant differences were reported for total (HDL and LDL) cholesterol and cholesterol:HDL ratio when all groups were included in the analysis (see Table 2). However, a significant group × time interaction was found for triglyceride levels (p < 0.05), with subsequent post-hoc analysis revealing a significant decrease in serum triglyceride levels in the CoQ10 compared to CON over the 2 week supplementation period (p < 0.05). It should be noted that triglyceride levels were below the normal range in both groups and such a decrease observed in the supplement group could primarily be due to normal physiological variation.

<p>Table 2</p>

Lipid Panels for the CoQ10 and Placebo (CON) groups.

Variable

Time

CoQ10

Placebo

Significance

Total Cholesterol (mg·dl-1)

Day 0

165 ± 32

172 ± 31

Group

0.126

Day 14

167 ± 25

182 ± 30

Time

0.151

G × T

0.621

Triglycerides (mg·dl-1)

Day 0

95 ± 42

78 ± 26

Group

0.552

Day 14

85 ± 43†

91 ± 36†

Time

0.985

G × T

0.019

HDL Cholesterol (mg·dl-1)

Day 0

53 ± 12

58 ± 15

Group

0.443

Day 14

54 ± 10

59 ± 15

Time

0.112

G × T

0.296

LDL Cholesterol (mg·dl-1)

Day 0

97 ± 28

99 ± 22

Group

0.827

Day 14

97 ± 24

104 ± 24

Time

0.004

G × T

0.121

Chol:HDL

Day 0

3.19 ± 0.81

3.07 ± 0.60

Group

0.431

Day 14

3.17 ± 0.74

3.19 ± 0.64

Time

0.183

G × T

0.201

Data are means and ± standard deviations of mean.

† represents p < 0.05 difference between groups

Nutritional intake and compliance

Nutritional intake was monitored over a 4-day period prior to each testing session and analyzed for energy intake, total carbohydrates, total protein and total fat (see Table 3). A significant group × time interaction was observed for total calories and protein (p < 0.05). No other statistically significant interactions were observed across groups.

<p>Table 3</p>

Nutritional Intake Analyses for the CoQ10 and Placebo (CON) groups.

Variable

Time

CoQ10

Placebo

Significance

Energy Intake (kcal·kg·d-1)

Baseline

2591 ± 613

2103 ± 598†

Group

0.210

Day 0

2668 ± 849

1979 ± 677†

Time

0.461

Day 14

2514 ± 474

2227 ± 608

G × T

0.023

Carbohydrate Intake (g·kg·-1·d-1)

Baseline

315 ± 85

267 ± 82

Group

0.420

Day 0

319 ± 116

247 ± 109

Time

0.410

Day 14

318 ± 66

287 ± 72

G × T

0.132

Protein Intake (g·kg·-1·d-1)

Baseline

114 ± 44

99 ± 32

Group

0.112

Day 0

124 ± 58

94 ± 34†

Time

0.243

Day 14

104 ± 35

102 ± 12

G × T

0.012

Fat Intake (g·kg·-1d·-1)

Baseline

97 ± 40

70 ± 23

Group

0.120

Day 0

104 ± 47

71 ± 28

Time

0.071

Day 14

90 ± 36

69 ± 23

G × T

0.081

Data are means and ± standard deviations of mean.

† represents p < 0.05 difference between groups

Body composition

Body composition was assessed at baseline, day 0 and 14 to determine changes in bone, fat and lean changes over the course of the investigation (see Table 4). No significant differences were observed between groups in changes in total body water, bone mass, lean body mass, or body fat percentage over the course of the investigation.

<p>Table 4</p>

Body Composition Measurements for the CoQ10 and Placebo (CON) groups.

Variable

Time

CoQ10

Placebo

Significance

BMC

Day 0

2805 ± 694

2584 ± 487

Group

0.352

(g)

Day 14

2788 ± 706

2596 ± 452

Time

0.485

G × T

0.219

Fat Mass (kg)

Day 0

15385 ± 7686

15128 ± 6307

Group

0.443

Day 14

15252 ± 7740

15284 ± 6342

Time

0.312

G × T

0.196

Lean Mass (kg)

Day 0

55274 ± 13638

51221 ± 11336

Group

0.627

Day 14

55260 ± 13794

51311 ± 11372

Time

0.214

G × T

0.121

Body Fat (%)

Day 0

21 ± 7.2

22 ± 7.0

Group

0.731

Day 14

21 ± 7.0

22 ± 6.9

Time

0.183

G × T

0.201

Data are means and ± standard deviations of mean

Muscle endurance assessment

A 50 repetition isokinetic leg extension test was performed at baseline, day 0, and day 14 to assess indices of muscle endurance performance (see Table 5). No statistically significant interactions were observed among groups in indices of muscle endurance (peak torque extension [EXT], peak torque flexion [FLX], total work EXT, total work FLX, work fatigue EXT, work fatigue FLX, average [AVG] power EXT, AVG power FLX).

<p>Table 5</p>

Isokinetic Muscle Endurance Indices for the CoQ10 and Placebo (CON) groups.

Variable

Time

CoQ10

Placebo

Significance

Peak Torque EXT (N/m)

Baseline

132 ± 42

110 ± 38

Group

0.181

Day 0

127 ± 37

110 ± 34

Time

0.265

Day 14

132 ± 34

107 ± 35

G × T

0.495

Peak Torque FLX (N/m)

Baseline

72 ± 28

65 ± 26

Group

0.218

Day 0

75 ± 28

66 ± 28

Time

0.534

Day 14

73 ± 24

65 ± 28

G × T

0.488

Total Work EXT (N/m)

Baseline

4047 ± 1218

3391 ± 992

Group

0.826

Day 0

3955 ± 1114

3352 ± 936

Time

0.308

Day 14

4073 ± 1116

3242 ± 921

G × T

0.442

Total Work FLX (N/m)

Baseline

2213 ± 847

1962 ± 891

Group

0.127

Day 0

2203 ± 877

1996 ± 963

Time

0.493

Day 14

2230 ± 822

1866 ± 839

G × T

0.591

Work Fatigue EXT (%)

Baseline

48 ± 15

41 ± 17

Group

0.112

Day 0

46 ± 14

37 ± 19

Time

0.160

Day 14

48 ± 11

36 ± 20

G × T

0.309

Work Fatigue FLX (%)

Baseline

46 ± 20

43 ± 29

Group

0.132

Day 0

51 ± 14

35 ± 30

Time

0.534

Day 14

51 ± 16

44 ± 14

G × T

0.192

AVG Power EXT (Watts)

Baseline

117 ± 36

95 ± 30

Group

0.476

Day 0

115 ± 34

95 ± 27

Time

0.315

Day 14

117 ± 33

95 ± 30

G × T

0.351

AVG Power FLX (Watts)

Baseline

61 ± 25

52 ± 25

Group

0.106

Day 0

62 ± 26

54 ± 27

Time

0.334

Day 14

62 ± 24

52 ± 26

G × T

0.402

Data are means and ± standard deviations of mean

Anaerobic capacity assessment

A 30 second Wingate anaerobic capacity test was performed at baseline, day 0, and day 14 to assess indices of anaerobic performance (see Table 6). No statistically significant interactions were observed among groups in anaerobic capacity indices (peak power, mean power, rate to fatigue, or total work). A trend towards a significant main effect for time was observed in rate to fatigue performance (p = 0.06), indicating an increase in rate to fatigue from baseline (T1) to day 14 (T3).

<p>Table 6</p>

Wingate Anaerobic Power Indices for the CoQ10 and Placebo (CON) groups.

Variable

Time

CoQ10

Placebo

Significance

Peak Power (Watts)

Baseline

1162 ± 436

1013 ± 417

Group

0.359

Day 0

1169 ± 421

1079 ± 416

Time

0.138

Day 14

1209 ± 420

1069 ± 400

G × T

0.587

Mean Power (Watts)

Baseline

592 ± 210

535 ± 181

Group

0.427

Day 0

594 ± 209

545 ± 180

Time

0.137

Day 14

603 ± 211

548 ± 181

G × T

0.883

Rate to Fatigue (Watts)

Baseline

33 ± 14

27 ± 15

Group

0.239

Day 0

34 ± 15

30 ± 15

Time

0.060

Day 14

35 ± 15

29 ± 14

G × T

0.623

Data are means and ± standard deviations of mean

Aerobic capacity assessment

A maximal graded exercise test was performed at baseline, day 0, and day 14 to assess aerobic capacity and performance (see Table 7). A trend towards a significant group × time interaction was observed in time to exhaustion (p = 0.06), indicating the CoQ10 group exercised longer compared to the CON group following 2 weeks of supplementation. No statistically significant interactions were observed across groups in other indices of aerobic capacity (i.e., oxygen consumption, RER, or ventilatory anaerobic threshold).

<p>Table 7</p>

Aerobic Power Indices for the CoQ10 and Placebo (CON) groups.

Variable

Time

CoQ10

Placebo

Significance

Oxygen Consumption (mL·kg-1·min-1)

Baseline

42.3 ± 9.1

43.9 ± 9.0

Group

0.358

Day 0

42.9 ± 8.5

45.5 ± 7.9

Time

0.815

Day 14

42.1 ± 8.5

43.4 ± 9.6

G × T

0.293

Maximal Respiratory Exchange Ratio

Baseline

1.16 ± 0.09

1.17 ± 0.08

Group

0.564

Day 0

1.18 ± 0.09

1.19 ± 0.04

Time

0.134

Day 14

1.16 ± 0.09

1.16 ± 0.11

G × T

0.546

Time to exhaustion (Min)

Baseline

12.9 ± 2.4

13.6 ± 2.3

Group

0.332

Day 0

13.1 ± 2.8

13.8 ± 2.1

Time

0.110

Day 14

13.3 ± 2.3

13.7 ± 2.4

G × T

0.060

Ventilatory Threshold (% VO2max)

Baseline

70.4 ± 12.9

71.35 ± 11.6

Group

0.210

Day 0

70.7 ± 11.4

72.30 ± 11.4

Time

0.951

Day 14

72.1 ± 12.0

70.00 ± 11.9

G × T

0.536

Data are means and ± standard deviations of mean

Markers of oxidative stress

Table 8 presents markers of oxidative stressed evaluated in this study. A significant main effect for time was observed in serum SOD levels, indicating an increase following all exercise performance measurements on day 0 (T2) and day 14 (T3). However, a trend towards a significant group × time interaction (p = 0.06) was revealed with subsequent post-hoc analysis indicating that although SOD levels increased over time. SOD levels after the isokinetic muscle endurance test were significantly lower in the CoQ10 compared to CON group (p < 0.05). A significant main effect for time was also observed in serum 8-ISO and MDA levels (p < 0.05 and p < 0.001, respectively) indicating an increase over time following all exercise performance measurements on day 0 (T2) and day 14 (T3). Similar to SOD levels, a significant group × time interaction (p < 0.05) was also revealed on day 0. However, post-hoc analysis indicated significantly lower MDA levels in the CON group compared to CoQ10 group following the anaerobic Wingate test and aerobic capacity test (p < 0.05). No other significant interactions were observed.

<p>Table 8</p>

Time Course of Markers of Oxidative Stress for the CoQ10 and Placebo (CON) subjects taken immediately after each performance test.

Variable

Time

CoQ10

Placebo

Significance

Superoxide Dismutase (SOD) (U/ml)

Baseline T2

1.52 ± 0.31

1.59 ± 0.27

Group

0.103

Isokinetic T2

1.56 ± 0.24

1.80 ± 0.39

Time

0.001

Wingate T2

1.75 ± 0.23

1.70 ± 0.22

G × T

0.060

GXT T2

1.68 ± 0.17

1.70 ± 0.26

Baseline T3

1.61 ± 0.40

1.77 ± 0.52

Group

0.296

Isokinetic T3

1.74 ± 0.37

1.90 ± 0.54

Time

0.001†

Wingate T3

1.91 ± 0.39

2.06 ± 0.51

G × T

0.966

GXT T3

1.81 ± 0.42

1.98 ± 0.50

Thiobarbituric Acid Reactive Substance (TBARS) (μM)

Baseline T2

2.79 ± 1.02

2.50 ± 1.34

Group

0.042

Isokinetic T2

4.11 ± 1.71

3.24 ± 1.69

Time

0.001

Wingate T2

4.72 ± 2.14

3.35 ± 1.57†

G × T

0.018†

GXT T2

5.09 ± 2.23

3.62 ± 1.90†

Baseline T3

3.03 ± 1.03

3.12 ± 1.26

Group

0.540

Isokinetic T3

4.28 ± 1.72

4.23 ± 1.47

Time

0.001

Wingate T3

4.25 ± 1.17

4.85 ± 2.11

G × T

0.534

GXT T3

5.32 ± 2.09

5.52 ± 1.89