Safety of a dose-escalated pre-workout supplement in recreationally active females

BACKGROUND

Pre-workout supplements (PWS) have increased in popularity among athletic populations for their purported ergogenic benefits. Most PWS contain a "proprietary blend" of several ingredients, such as caffeine, beta-alanine, and nitrate in undisclosed dosages. Currently, little research exists on the safety and potential side effects of chronic consumption of PWS, and even less so involving female populations. Therefore, the purpose of the present study was to examine the safety of consuming a dose-escalated PWS over a 28-day period among active adult females.

METHODS

34 recreationally active, adult females (27.1 ± 5.4 years, 165.2 ± 5.7 cm, 68.2 ± 16.0 kg) participated in this study. Participants were randomly assigned to consume either 1 (G1) or 2 (G2) servings of a PWS daily or remain unsupplemented (CRL) for a period of 28 days. All were instructed to maintain their habitual dietary and exercise routines for the duration of the study. Fasting blood samples, as well as resting blood pressure and heart rate, were taken prior to and following the supplementation period. Samples were analyzed for hematological and clinical chemistry panels, including lipids.

RESULTS

Significant (p < 0.05) group by time interactions were present for absolute monocytes (CRL -0.10 ± 0.10; G1 + 0.03 ± 0.13; G2 + 0.01 ± 0.12×10E3/uL), MCH (CRL -0.13 ± 0.46; G1 + 0.36 ± 0.52; G2 -0.19 ± 0.39 pg), creatinine (CRL 0.00 ± 0.05; G1 -0.06 ± 0.13; G2 -0.14 ± 0.08 mg/dL), eGFR (CRL -0.69 ± 5.97; G1 + 6.10 ± 15.89; G2 + 14.63 ± 7.11 mL/min/1.73), and total cholesterol (CRL -2.44 ± 13.63; G1 + 14.40 ± 27.32; G2 -10.38 ± 15.39 mg/dL). Each of these variables remained within the accepted physiological range. No other variables had significant interactions.

CONCLUSION

The present study confirms the hypothesis that a PWS containing caffeine, beta-alanine, and nitrate will not cause abnormal changes in hematological markers or resting vital signs among adult females. Although there were statistically significant (p < 0.05) group by time interactions for absolute monocytes, MCH, creatinine, eGFR, and total cholesterol, all of the results remained well within accepted physiological ranges and were not clinically significant. In sum, it appears as though daily supplementation with up to 2 servings of the PWS under investigation, over an interval of 28 days, did not adversely affect markers of clinical safety among active adult females.

An amino acid-electrolyte beverage may increase cellular rehydration relative to carbohydrate-electrolyte and flavored water beverages

BACKGROUND

In cases of dehydration exceeding a 2% loss of body weight, athletic performance can be significantly compromised. Carbohydrate and/or electrolyte containing beverages have been effective for rehydration and recovery of performance, yet amino acid containing beverages remain unexamined. Therefore, the purpose of this study is to compare the rehydration capabilities of an electrolyte-carbohydrate (EC), electrolyte-branched chain amino acid (EA), and flavored water (FW) beverages.

METHODS

Twenty men (n = 10; 26.7 ± 4.8 years; 174.3 ± 6.4 cm; 74.2 ± 10.9 kg) and women (n = 10; 27.1 ± 4.7 years; 175.3 ± 7.9 cm; 71.0 ± 6.5 kg) participated in this crossover study. For each trial, subjects were dehydrated, provided one of three random beverages, and monitored for the following three hours. Measurements were collected prior to and immediately after dehydration and 4 hours after dehydration (3 hours after rehydration) (AE = -2.5 ± 0.55%; CE = -2.2 ± 0.43%; FW = -2.5 ± 0.62%). Measurements collected at each time point were urine volume, urine specific gravity, drink volume, and fluid retention.

RESULTS

No significant differences (p > 0.05) existed between beverages for urine volume, drink volume, or fluid retention for any time-point. Treatment x time interactions existed for urine specific gravity (USG) (p < 0.05). Post hoc analysis revealed differences occurred between the FW and EA beverages (p = 0.003) and between the EC and EA beverages (p = 0.007) at 4 hours after rehydration. Wherein, EA USG returned to baseline at 4 hours post-dehydration (mean difference from pre to 4 hours post-dehydration = -0.0002; p > 0.05) while both EC (-0.0067) and FW (-0.0051) continued to produce dilute urine and failed to return to baseline at the same time-point (p < 0.05).

CONCLUSION

Because no differences existed for fluid retention, urine or drink volume at any time point, yet USG returned to baseline during the EA trial, an EA supplement may enhance cellular rehydration rate compared to an EC or FW beverage in healthy men and women after acute dehydration of around 2% body mass loss.

Ingesting a preworkout supplement containing caffeine, creatine, β-alanine, amino acids, and B vitamins for 28 days is both safe and efficacious in recreationally active men

The purpose of this study was to determine the safety and efficacy of consuming a preworkout supplement (SUP) containing caffeine, creatine, β-alanine, amino acids, and B vitamins for 28 days. We hypothesized that little to no changes in kidney and liver clinical blood markers or resting heart rate and blood pressure (BP) would be observed. In addition, we hypothesized that body composition and performance would improve in recreationally active males after 28 days of supplementation. In a double-blind, placebo-controlled study, participants were randomly assigned to ingest one scoop of either the SUP or placebo every day for 28 days, either 20 minutes before exercise or ad libitum on nonexercise days. Resting heart rate and BP, body composition, and fasting blood samples were collected before and after supplementation. Aerobic capacity as well as muscular strength and endurance were also measured. Significant (P < .05) main effects for time were observed for resting heart rate (presupplementation, 67.59 ± 7.90 beats per minute; postsupplementation, 66.18 ± 7.63 beats per minute), systolic BP (presupplementation, 122.41 ± 11.25 mm Hg; postsupplementation, 118.35 ± 11.58 mm Hg), blood urea nitrogen (presupplementation, 13.12 ± 2.55 mg/dL; postsupplementation, 15.24 ± 4.47 mg/dL), aspartate aminotransferase (presupplementation, 34.29 ± 16.48 IU/L; postsupplementation, 24.76 ± 4.71 IU/L), and alanine aminotransferase (presupplementation, 32.76 ± 19.72 IU/L; postsupplementation, 24.88 ± 9.68 IU/L). Significant main effects for time were observed for body fat percentage (presupplementation, 15.55% ± 5.79%; postsupplementation, 14.21% ± 5.38%; P = .004) and fat-free mass (presupplementation, 70.80 ± 9.21 kg; postsupplementation, 71.98 ± 9.27 kg; P = .006). A significant decrease in maximal oxygen consumption (presupplementation, 47.28 ± 2.69 mL/kg per minute; postsupplementation, 45.60 ± 2.81 mL/kg per minute) and a significant increase in percentage of oxygen consumption per unit time at which ventilatory threshold occurred (presupplementation, 64.38% ± 6.63%; postsupplementation, 70.63% ± 6.39%) and leg press one-repetition maximum (presupplementation, 218.75 ± 38.43 kg; postsupplementation, 228.75 ± 44.79 kg) were observed in the SUP only. No adverse effects were noted for renal and hepatic clinical blood markers, resting heart rate, or BP. Supplements containing similar ingredients and doses should be safe for ingestion periods lasting up to 28 days in healthy, recreationally trained, college-aged men.

Simplified method of clinical phenotyping for older men and women using established field-based measures

The purpose of this investigation was to determine body composition classification using field-based testing measurements in healthy elderly men and women. The use of isoperformance curves is presented as a method for this determination. Baseline values from 107 healthy Caucasian men and women, over the age of 65years old, who participated in a separate longitudinal study, were used for this investigation. Field-based measurements of age, height, weight, body mass index (BMI), and handgrip strength were recorded on an individual basis. Relative skeletal muscle index (RSMI) and body fat percentage (FAT%) were determined by dual-energy X-ray absorptiometry (DXA) for each participant. Sarcopenia cut-off values for RSMI of 7.26kg·m(-2) for men and 5.45kg·m(-2) for women and elderly obesity cut-off values for FAT% of 27% for men and 38% for women were used. Individuals above the RSMI cut-off and below the FAT% cut-off were classified in the normal phenotype category, while individuals below the RSMI cut-off and above the FAT% cut-off were classified in the sarcopenic-obese phenotype category. Prediction equations for RSMI and FAT% from sex, BMI, and handgrip strength values were developed using multiple regression analysis. The prediction equations were validated using double cross-validation. The final regression equation developed to predict FAT% from sex, BMI, and handgrip strength resulted in a strong relationship (adjusted R(2)=0.741) to DXA values with a low standard error of the estimate (SEE=3.994%). The final regression equation developed to predict RSMI from the field-based testing measures also resulted in a strong relationship (adjusted R(2)=0.841) to DXA values with a low standard error of the estimate (SEE=0.544kg·m(-2)). Isoperformance curves were developed from the relationship between BMI and handgrip strength for men and women with the aforementioned clinical phenotype classification criteria. These visual representations were used to aid in the classification and evaluation of sarcopenia, obesity, and sarcopenic-obesity in elderly individuals. Future research should replicate the current findings with an increased sample size and the development of tailored interventions for each body composition category.

Ingesting a pre-workout supplement containing caffeine, B-vitamins, amino acids, creatine, and beta-alanine before exercise delays fatigue while improving reaction time and muscular endurance

BACKGROUND

The purpose of this study was to determine the effects of the pre-workout supplement Assault™ (MusclePharm, Denver, CO, USA) on upper and lower body muscular endurance, aerobic and anaerobic capacity, and choice reaction time in recreationally-trained males. Subjective feelings of energy, fatigue, alertness, and focus were measured to examine associations between psychological factors and human performance.

METHODS

Twelve recreationally-trained males participated in a 3-week investigation (mean +/- SD, age: 28 +/- 5 y, height: 178 +/- 9 cm, weight: 79.2 +/- 15.7 kg, VO2max: 45.7 +/- 7.6 ml/kg/min). Subjects reported to the human performance laboratory on three separate occasions. All participants completed a baseline/familiarization day of testing that included a maximal graded exercise test for the determination of aerobic capacity (VO2max), one-rep maximum (1-RM) for bench and leg press to determine 75% of 1-RM, choice reaction tests, and intermittent critical velocity familiarization. Choice reaction tests included the following: single-step audio and visual, one-tower stationary protocol, two-tower lateral protocol, three-tower multi-directional protocol, and three-tower multi-directional protocol with martial arts sticks. Subjects were randomly assigned to ingest either the supplement (SUP) or the placebo (PL) during Visit 2. Subjects were provided with the cross-over treatment on the last testing visit. Testing occurred 20 min following ingestion of both treatments.

RESULTS

Significant (p < 0.05) main effects for the SUP were observed for leg press (SUP: 13 ± 6 reps, PL: 11 ± 3 reps), perceived energy (SUP: 3.4 ± 0.9, PL: 3.1 ± 0.8), alertness (SUP: 4.0 ± 0.7, PL: 3.5 ± 0.8), focus (SUP: 4.1 ± 0.6, PL: 3.5 ± 0.8), choice reaction audio single-step (SUP: 0.92 ± 0.10 s, PL: 0.97 ± 0.11 s), choice reaction multi-direction 15 s (SUP: 1.07 ± 0.12 s, PL: 1.13 ± 0.14 s), and multi-direction for 30 s (SUP: 1.10 ± 0.11 s, PL: 1.14 ± 0.13 s).

CONCLUSIONS

Ingesting the SUP before exercise significantly improved agility choice reaction performance and lower body muscular endurance, while increasing perceived energy and reducing subjective fatigue. These findings suggest that the SUP may delay fatigue during strenuous exercise.

Mechanical scale and load cell underwater weighing: a comparison of simultaneous measurements and the reliability of methods

Both load cell and mechanical scale-based hydrostatic weighing (HW) systems are used for the measurement of underwater weight. However, there has been no direct comparison of the 2 methods. The purpose of the current investigation was to simultaneously compare a load cell and mechanical scale for use in HW. Twenty-seven men and women (mean ± SD, age: 22 ± 2 years) participated in the 2-day investigation. Each subject completed 2 HW assessments 24 hours apart. Single-day comparisons of all trials for both days revealed no significant difference between the mechanical scale and the load cell (mean difference < 0.016 kg, p > 0.05). True underwater weight values were not significantly different between methods for either days (mean difference < 0.014 kg, p > 0.05) and accounted for a mean difference in percent fat (%FAT) of <0.108%. The 95% limits of agreement indicated a maximum difference between methods of 0.53% FAT. Both methods produced similar reliability SEM values (mechanical SEM < 0.72%FAT, load cell SEM < 0.75%FAT). In conclusion, there was no difference between mechanical scale and load cell measurements of underwater weights and the added precision of the load cell only marginally (<0.16%FAT) improved day-to-day reliability. Either a mechanical scale or load cell can be used for HW with similar accuracy and reliability in young adults with a body mass index of 18.7-34.4 (5-25%FAT).

Low-calorie energy drink improves physiological response to exercise in previously sedentary men: a placebo-controlled efficacy and safety study

Energy drink use has grown despite limited research to support efficacy or safety and amid concerns when combined with exercise. The purpose of this study was to assess the effects of 10 weeks of once-daily energy drink consumption or energy drink consumption with exercise on measures of body composition, cardiorespiratory fitness, strength, mood, and safety in previously sedentary males. Thirty-eight males were randomly assigned to energy drink + exercise (EX-A), energy drink (NEX-A), placebo + exercise (EX-B), or placebo (NEX-B). All participants consumed 1 drink per day for 10 weeks; EX-A and EX-B participated in 10 weeks of resistance and endurance exercise. Testing was performed before (PRE) and after (POST) the 10-week intervention. No significant (p > 0.05) changes were observed for body composition, fitness, or strength in NEX-A; however, significantly greater decreases in fat mass and percentage body fat and increases in VO2peak were observed in EX-A versus EX-B. Ventilatory threshold (VT), minute ventilation, VO2 at VT, and power output at VT improved significantly PRE to POST in EX-A but not in EX-B or nonexercising groups. Clinical markers for hepatic, renal, cardiovascular, and immune function, as determined by PRE and POST blood work revealed no adverse effects in response to the energy drink. Mood was not affected by energy drink use. Absent energy restriction or other dietary controls, chronic ingestion of a once-daily low-calorie energy drink appears ineffective at improving body composition, cardiorespiratory fitness, or strength in sedentary males. However, when combined with exercise, preworkout energy drink consumption may significantly improve some physiological adaptations to combined aerobic and resistance training.

Physiological effects of caffeine, epigallocatechin-3-gallate, and exercise in overweight and obese women

The aim of this study was to evaluate the combined effects of a 10-week exercise program with ingestion of caffeine and epigallocatechin-3-gallate (EGCG) on body composition, cardiovascular fitness, and strength in overweight and obese women. In a double-blind, placebo-controlled approach, overweight and obese women (n = 27) were randomly assigned to treatment groups with exercise (an active-supplementing group with exercise (EX-Act) and a placebo group with exercise (EX-PL)) or without exercise (an active-supplementing group without exercise (NEX-Act) and a placebo group without exercise (NEX-PL)). All participants consumed 1 drink per day for 10 weeks; EX-Act and EX-PL participated in a concurrent endurance and resistance training program. Changes in body composition were assessed using a 4-compartment model. Changes in muscle mass (MM) were evaluated using a DXA-derived appendicular lean–soft tissue equation. There was a significant time × treatment interaction for MM (p = 0.026) and total cholesterol (TC) (p = 0.047), and a significant time × training interaction for peak oxygen consumption (p = 0.046) and upper-body and lower-body strength (p < 0.05). Significant differences between the EX groups and NEX groups for percentage change in MM and peak oxygen consumption, and upper-body and lower-body strength, were revealed. Clinical markers for hepatic and renal function revealed no adverse effects. TC significantly decreased for the active-supplementing groups (EX-Act, NEX-Act). The current study suggests that implementing a caffeine–EGCG-containing drink prior to exercise may improve MM, fitness, and lipid profiles in overweight women.

The effects of four weeks of creatine supplementation and high-intensity interval training on cardiorespiratory fitness: a randomized controlled trial

Background

High-intensity interval training has been shown to be a time-efficient way to induce physiological adaptations similar to those of traditional endurance training. Creatine supplementation may enhance high-intensity interval training, leading to even greater physiological adaptations. The purpose of this study was to determine the effects of high-intensity interval training (HIIT) and creatine supplementation on cardiorespiratory fitness and endurance performance (maximal oxygen consumption (VO_2PEAK), time-to-exhaustion (VO_2PEAKTTE), ventilatory threshold (VT), and total work done (TWD)) in college-aged men.

Methods

Forty-three recreationally active men completed a graded exercise test to determine VO_2PEAK, VO_2PEAKTTE, and VT. In addition, participants completed a time to exhaustion (TTE) ride at 110% of the maximum workload reached during the graded exercise test to determine TWD (TTE (sec) × W = J). Following testing, participants were randomly assigned to one of three groups: creatine (creatine citrate) (Cr; n = 16), placebo (PL; n = 17), or control (n = 10) groups. The Cr and PL groups completed four weeks of HIIT prior to post-testing.

Results

Significant improvements in VO_2PEAK and VO_2PEAKTTE occurred in both training groups. Only the Cr group significantly improved VT (16% vs. 10% improvement in PL). No changes occurred in TWD in any group.

Conclusion

In conclusion, HIIT is an effective and time-efficient way to improve maximal endurance performance. The addition of Cr improved VT, but did not increase TWD. Therefore, 10 g of Cr per day for five days per week for four weeks does not seem to further augment maximal oxygen consumption, greater than HIIT alone; however, Cr supplementation may improve submaximal exercise performance.