Astaxanthin Reduces Heart Rate and Carbohydrate Oxidation Rates During Exercise in Overweight Individuals.

Astaxanthin (AX) is an antioxidant which may spare endogenous carbohydrates and improve fat oxidation rates, thus improving metabolic flexibility. To date, no studies have attempted to examine the impact of AX in an overweight cohort, whom often suffer from metabolic inflexibility. Nineteen subjects (mean ± SD: age: 27.5 ± 6.3 years; height: 169.7 ± 9.0 cm; body mass: 96.4 ± 17.9 kg; BF%: 37.9 ± 7.0%; BMI: 33.4 ± 5.6 kg/m2; VO2peak: 25.9 ± 6.7 ml·kg-1·min-1) were recruited and supplemented with either 12 mg of AX or placebo (PLA) for 4 weeks. Subjects completed a graded exercise test on a cycling ergometer to examine changes in substrate oxidation rates. A total of 5 stages, each lasting 5 min and resistance increased 15 W each stage, were completed to examine changes in levels of glucose and lactate, fat and carbohydrate (CHO) oxidation rates, heart rate, and rating of perceived exertion (RPE). Although there were no changes found in rates of fat oxidation, blood lactate or glucose, or RPE (all p > 0.05), a significant decrease was observed in CHO oxidation from pre to post supplementation in the AX group only. Further, the AX group demonstrated a 7% decrease in heart rate across the graded exercise test. These findings suggest that 4 weeks of AX supplementation may offer some cardiometabolic benefits to overweight individuals, and be a favorable supplement for these individuals beginning an exercise program.

A Self-Selected 16:8 Time-Restricted Eating Protocol Improves Fat Oxidation Rates, Markers of Cardiometabolic Health, and 10-km Cycling Performance in Middle-Age Male Cyclists.

ABSTRACT: Witt, CR, Grozier, CD, Killen, LG, Renfroe, LG, O'Neal, EK, and Waldman, HS. A self-selected 16:8 time-restricted eating protocol improves fat oxidation rates, markers of cardiometabolic health, and 10-km cycling performance in middle-age male cyclists. J Strength Cond Res 37(5): 1117-1123, 2023-The purpose of this study was to assess the impact of 4 weeks, 16:8 time restricted eating (TRE) on markers of metabolic health and 10-km time trial (TT) performance in middle-age male cyclists. Subjects ( n = 12; age, 40-60 years; V̇ o2 peak, 41.8 ± 5.6 ml·kg -1 ·min -1 ) consisting of individuals following a habitual Western diet completed a familiarization and 2 experimental trials [PRE] and [POST]. Following habitual Western diet without TRE, anthropometric measures were assessed, followed by completion of a graded exercise test and 10-km TT. Subjects then adhered to a 4-week TRE protocol where all calories had to be consumed within a self-selected 8-hour window and then returned for repeat testing. Although self-reported caloric intake did not statistically change PRE to POST, body mass (PRE, 83.2 ± 13.4 vs. POST, 80.7 ± 12.6 kg), fat mass (∼2.5 kg), and blood pressure (systolic, 8 mm Hg; diastolic, 4 mm Hg) were all significantly lower POST (all p < 0.05), with no changes in fat-free mass. Furthermore, fat oxidation significantly increased (PRE, 0.36 ± 0.03 vs. POST, 0.42 ± 0.03 g·min -1 ; p = 0.04) following the TRE intervention and 10-km TT performance improved by ∼2 minutes POST (PRE, 29.7 ± 7.3 vs. POST, 27.4 ± 5.5 minutes; p = 0.02). Overall, our data demonstrated that middle-age male cyclists adhering to a 4-week TRE protocol can improve their body composition profile and 10-km TT performance without detriments to fat-free mass.

Assessment of Metabolic Flexibility by Substrate Oxidation Responses and Blood Lactate in Women Expressing Varying Levels of Aerobic Fitness and Body Fat.

ABSTRACT: Waldman, HS, Bryant, AR, Knight, SN, Killen, LG, Davis, BA, Robinson, MA, and O'Neal, EK. Assessment of metabolic flexibility by substrate oxidation responses and blood lactate in women expressing varying levels of aerobic fitness and body fat. J Strength Cond Res 37(3): 581-588, 2023-Collection of substrate oxidation responses during exercise is proposed as a noninvasive means for assessing metabolic flexibility in male subjects. However, because of hormonal and metabolic differences between sexes, this method may not be applicable to female subjects. This study assessed metabolic flexibility through indirect calorimetry across female subjects with different maximal oxidative capacities. Thirty-eight (18-45 years) eumenorrheic female subjects were stratified ( p < 0.05) based on V̇ o2 peak (mL·kg -1 ·min -1 ) into (1) endurance-trained (ET, n = 12, 42.6 ± 5.3), (2) recreationally active (RA, n = 13, 32.3 ± 1.6), or (3) overweight female subjects (OW, n = 13, 21.0 ± 4.0). Subjects completed the same 5-stage graded exercise test with intensities of 30, 45, 60, 75, and 90 W. Lactate [La - ], carbohydrate (CHOox), and fat (FATox) oxidation rates were assessed during the last min of each 5-minute stage. Subjects then cycled to exhaustion to determine V̇ o2 peak. Endurance-trained and RA female subjects expressed significantly ( p ≤ 0.05) higher absolute rates and rates scaled to fat-free mass of CHOox and FATox compared with OW female subjects during multiple stages. [La - ] failed to consistently differentiate the 3 groups with higher [La - ] for OW only found during stage 4; however, RER differed by 0.09 units or more at each stage for OW vs. ET. It seems that RER was more sensitive to cohort characteristics than [La - ] contrasting recent findings in male cohorts. In conclusion, indirect calorimetry is a practical and noninvasive method for assessing metabolic flexibility in eumenorrheic female subjects of varying aerobic fitness levels.

Effects of 3 Weeks Yogic Breathing Techniques on Sub-maximal Running Responses.

This study investigated the influence of yoga breathing techniques (YBT) on physiological and perceptual responses during sub-maximal treadmill running. Runners (n = 21) of various fitness (VO2max 48.4 ± 9.5 ml/kg/min) were assigned to Yoga (YG) or control (CT) group before completing pre/post treadmill trials where velocity was self-selected to produce an RPE 4 and RPE 7 (10 min each). YG (n =11) practiced three styles of YBT (30 min/day, 6 days/wk) for 3 consecutive wks. Self-selected running velocity for YG improved significantly at both prescribed RPE 4 (pre 157.63 ± 26.20 M/min, post 181.02 ± 24.22 M/min, p = 0.01) and prescribed RPE 7 (pre 201.97 ± 31.28 M/min, post 222.68± 35.32 M/min, p = 0.01). VO2 at RPE 7 increased significantly (pre 42.6 ± 6.9 ml/kg/min, post 47.3 ± 6.2 ml/kg/min, p = 0.02), TV at RPE 7 (pre 1.81 ± 0.30, post 2.04 ± 0.41, p = 0.01), and MV at RPE 7 (pre 77.25 ± 12.42, post 91.23 ± 20.05, p = 0.01). The CT group showed no significant changes except for TV at RPE 7 (pre 1.9 ± 0.3, post 2.0 ± 0.3, p = 0.04). Current results suggest YBT positively influences running velocity regulation during self-selected running.

Four Weeks of Hericium erinaceus Supplementation Does Not Impact Markers of Metabolic Flexibility or Cognition.

Hericium erinaceus (HE), also known as Lion's Mane mushroom, has been found to enhance cognition and metabolic flexibility in various animal models. To date however, only four studies exist in humans and none have evaluated the effects of HE on markers of metabolic flexibility or cognitive performance. A single-blind, placebo controlled, parallel-longitudinal study was used to determine the effects of HE on markers of metabolic flexibility and cognition. Twenty-four participants completed a graded exercise test on a cycle ergometer to analyze substrate oxidation rates and markers of cardiorespiratory fitness. Additionally, two dual-task challenges consisting of a Stroop Word Challenge interspersed with a Mental Arithmetic Challenge were performed, pre-post the graded exercise test, to evaluate markers of cognition in a pre-post fatigued state. Participants were stratified into two groups, receiving either 10 g of HE per day or placebo for 4-weeks in the form of two muffins identical in taste and appearance. Repeated-measures analysis of variance were conducted to evaluate potential interactions or main effects. Although group differences were noted at baseline, there were no significant interactions or main effects observed from HE ingestion for any dependent variable (all p > 0.05). Our data suggest that ingesting 10 g of HE per day for 4-weeks had no impact on metabolic flexibility and cognition in a college-age cohort. Due to the limited research on HE supplementation, future research is needed to establish an effective supplement dose and duration for potential physiological changes to be observed in humans.

Exergaming for physical activity: A systematic review.

OBJECTIVE: This review evaluates current literature on intensity selection, perceptual responses, activity enjoyment and adherence rates of exergaming. METHODS: The literature search identified manuscripts that investigated exercise intensity, perceptual responses, or exercise adherence of exergaming in young adults. RESULTS: Based on results of 29 studies, the current review suggest some exergaming activities have the potential to elicit moderate to vigorous exercise intensity and could potentially be substituted for traditional exercise. Additionally, exergame activities may aid in the start of exercise adherence by lowering the individual's perceived exertion when playing exergames. Exergaming not only has the potential to enhance enjoyment through an exercise objective but also through the distracting nature of video games. CONCLUSIONS: Exergaming shows potential to be substituted for traditional exercise and could offer a new, varied form of exercise for sedentary individuals. Future research should examine the influence of exergaming experience on intensity selection and adherence rates.

Effects of Magnesium Supplementation on Muscle Soreness and Performance.

ABSTRACT: Reno, AM, Green, M, Killen, LG, O'Neal, EK, Pritchett, K, and Hanson, Z. Effects of magnesium supplementation on muscle soreness and performance. J Strength Cond Res 36(8): 2198-2203, 2022-This double-blind, between-group study examined effects of magnesium (Mg) supplementation (350 mg·d -1 , 10 days) on muscle soreness and performance. College-aged male ( n = 9) and female ( n = 13) subjects completed baseline and posttreatment eccentric bench press sessions inducing fatigue/soreness followed by performance sessions (total volume and repetitions to failure [RTF] [65, 75, and 85% of 1 repetition maximum]) 48 hours later with perceptual measures. Subjects estimated soreness using a Delayed Onset of Muscle Soreness scale by striking a vertical line on a 6-cm horizontal line (at 24, 36, and 48 hours post trial) from 0-no soreness to 6-intolerable soreness. Results are presented as means ± SD (alpha ≤0.05). Mg significantly reduced (∼1-2 units lower on a 6-point scale) muscle soreness from the baseline eccentric to postintervention trial 24, 36, and 48 hours with no significant change for placebo (Pla) group. Performance approached significance for total RTF ( p = 0.06) and 65 and 75% RTF ( p = 0.08) (Mg vs. Pla). Perceptual responses for session rating of perceived exertion and acute rating of perceived exertion were significant for Mg (5.1 ± 2.4 to 4.1 ± 2.0) vs. Pla (5.0 ± 1.8 to 5.5 ± 1.6). Perceived recovery after supplementation was improved vs. baseline for Mg (5.4 ± 2.2 to 7.5 ± 2.3) but not for Pla (6.2 ± 2.4 to 7.2 ± 3.3). Results show significantly reduced muscle soreness, session rating of perceived exertion, acute rating of perceived exertion, and improved perceived recovery after Mg (vs. Pla) supplementation and some evidence for positive performance impact.

Effects of 2.4 kg of Proximal External Loading on 5-km Running Performance.

ABSTRACT: Sharp, DW, Swain, JC, Boy, TG, Killen, LG, Green, JM, and O'Neal, EK. Effects of 2.4 kg of proximal external loading on 5-km running performance. J Strength Cond Res 36(7): 1833-1838, 2022-Racing weight is a popular topic in the running community. This study examined effects of modest loading via a ∼2.4-kg soft and malleable weighted compression garment on overground running performance. Former and current collegiate cross-country runners (5 women and 6 men) completed 2 outdoor, solo road course runs 7 days apart on a familiar training route. During the first run (CON) subjects ran as closely as possible to their goal pace for a "hard speed day" workout based on predetermined paces according to current training level. During a subsequent run, subjects attempted to match their pace with aid from global positioning system watches and splits verbally announced on the course while wearing the weighted compression garment (LOAD). Metabolic data was later assessed during 5-minute running bouts on a treadmill with CON and LOAD conditions at subject's CON run pace. LOAD was slower (p < 0.01) at the 1.6-km mark (6:03 ± 0:37 vs. 6:13 ± 0:40) and finish (18:29 ± 2:06 vs. 19:15 ± 2:16). There was no differentiation (p > 0.05) between V̇o2 (CON 3.47 ± 0.86; LOAD 3.56 ± 0.77 L·min-1) or respiratory exchange ratio (CON 1.05 ± 0.06; LOAD 1.06 ± 0.04) during the 5-minute running economy bouts. There was an inverse (r = -0.42) but nonsignificant (p = 0.22) relationship between percent difference in body mass and percent difference in performance. Metabolic variable differentiation was not detectable at race pace, but 2.4 kg of proximal loading resulted in an approximately 4% acute performance impairment.

A 3-Week, Low-Carbohydrate, High-Fat Diet Improves Multiple Serum Inflammatory Markers in Endurance-Trained Males.

ABSTRACT: Waldman, HS, Heatherly, AJ, Killen, LG, Hollingsworth, A, Koh, Y, and O'Neal, EK. A three-week, low-carbohydrate, high-fat diet improves multiple serum inflammatory markers in endurance-trained males. J Strength Cond Res 36(9): 2502-2508, 2022-This study examined the effects of a low-carbohydrate, high-fat diet (LCHF) on inflammatory marker responses in middle-aged endurance athletes. Eight male runners maintained their habitual mixed diet (HMD) in the first phase of the study before switching to a noncalorically restricted LCHF diet (∼70% of kcals from fat; carbohydrate <50 g) for 3 weeks. Subjects completed a 50-minute fixed pace treadmill running protocol in a hot environment, followed by a 5-km outdoor time trial. Fasting serum samples were collected immediately after exercise and heat stress restriction, and again 24 hours after the exercise/heat stressor. Thirty inflammation markers were assessed using the multiplex flow immunoassay technique. Seven markers (BAFF/TNFSF-13, sCD30/TNFRSF8, sCD163, Chitinase3-like1, gp130SIL-6Rß, sTNFR-1, and sTNFR-2) reached statistical significance ( p < 0.05) favoring LCHF before exercise, and sCD30/TNFRSF8 favored ( p < 0.05) LCHF before (HMD = 459 ± 111; LCHF = 296 ± 100) and after (HMD = 385 ± 104; LCHF = 285 ± 104 pg·ml -1 ) exercise. Although the current dietary intervention was short in duration, LCHF seems to offer some protection against multiple chronic inflammation markers for physically active men between ages 30 and 50 years.

The Cardiometabolic Health Benefits of Sauna Exposure in Individuals with High-Stress Occupations. A Mechanistic Review.

Components of the metabolic syndrome (i.e., hypertension, insulin resistance, obesity, atherosclerosis) are a leading cause of death in the United States and result in low-grade chronic inflammation, excessive oxidative stress, and the eventual development of cardiometabolic diseases (CMD). High-stress occupations (HSO: firefighters, police, military personnel, first responders, etc.) increase the risk of developing CMD because they expose individuals to chronic and multiple stressors (i.e., sleep deprivation, poor nutrition habits, lack of physical activity, psychological stress). Interestingly, heat exposure and, more specifically, sauna bathing have been shown to improve multiple markers of CMD, potentially acting as hormetic stressors, at the cellular level and in the whole organism. Therefore, sauna bathing might be a practical and alternative intervention for disease prevention for individuals with HSO. The purpose of this review is to detail the mechanisms and pathways involved in the response to both acute and chronic sauna bathing and collectively present sauna bathing as a potential treatment, in addition to current standard of care, for mitigating CMD to both clinicians and individuals serving in HSO.

Caffeinated Gum Does Not Influence RPE-Regulated Cadence in Recreationally-Active College Females Regardless of Habitual Caffeine Consumption.

Caffeine (CAF) has been extensively studied for its ergogenic and analgesic effects during exercise. However, the majority of these studies have been conducted in male populations. This study investigated the effects of acute CAF chewing gum on self-selected exercise intensity during a rating of perceived exertion (RPE) production trial in active females (n = 16, 21.0 ± 2.8 y). Data were also analyzed based on habitual CAF consumption level. Participants completed a V̇O2peak trial, followed by a familiarization and two randomized, triple-blinded experimental RPE production trials on an arm ergometer [clamped resistance, blinded to self-selected cadence (CAD)] with either CAF gum (300 mg; 4.8 ± 0.7 mg/kg-1 body mass) or placebo (PLA), at a prescribed RPE of 4 and 7 (10 min each). Self-selected CAD did not statistically differ (p > 0.05) between CAF or PLA for an RPE4 (37.7 ± 1.6 vs. 37.6 ± 1.6 rev·min-1) or RPE7 (42.9 ± 1.6 vs. 41.2 ± 1.7 rev·min-1), respectively. There were no statistical differences between treatment groups for any other variables, except restlessness rating which was significantly higher (3.5 vs. 2.2; p = 0.03, d = 0.64) for the CAF group compared to PLA. Secondary analysis revealed no statistical differences for any variables between habitual consumers of low (23 ± 20 mg/day) or mod/high (195 ± 93 mg/day) CAF. Our data support previous studies examining CAF in women across different testing modalities and suggest that regardless of habitual CAF consumption, females might require higher doses of CAF to replicate subjective and physiological responses commonly observed using similar RPE production protocols in male participants. These findings support the need for additional investigations into female physiological and perceptual responses following CAF ingestion.

Effects of Three Modest Levels of Proximal Loading on Marathon Pace Running Economy.

This study examined the effect of modest increases in proximal body mass on running economy expressed as metabolic cost (MC). External loads of 1.6 (L), 2.4 (M), and 3.2 kg (H) were added to the anterior and posterior torso region of male (n = 18) and female (n = 18) runners using a double-layered compression garment with gel inserts. MC was evaluated using stoichiometry equations of data collected via indirect calorimetry. Data was collected during four, 5-min running bouts at marathon pace for the 3 load levels and an unloaded state (CON). When data from both sexes were combined, MC for CON (13.2 ± 2.7) was lower (p < 0.05) versus L (13.5 ± 2.6), M (13.6 ± 2.6), and H (13.7 ± 2.6 kcal/min), but L did not differ from CON when data was analyzed for each sex. Male runners exhibited stepped increases in MC across loads and a weak-moderate relationship (r = 0.37; p < 0.01) between percentage change in absolute MC and increased percent body mass. A prediction model for MC (Δ% kcal/min = 0.98(Δ% body mass) - 0.91; SEE = ± 2.5%) was developed. For female runners, L increased MC by ~3.5% above CON, but no differentiation was found among L, M, and H, limiting the development of a prediction equation for females. Modest increases in body mass can produce detectable and potentially important levels of running economy impairment, but the relationship between changes in body mass and RE are complex, particularly in regards to sex.

Effects of 3 Weeks Yogic Breathing Practice on Ventilation and Running Economy.

Yogic breathing techniques (Pranayama) positively impact respiratory function (RF) in non-endurance trained individuals. The purpose of this study investigated effects of routine Pranayama practice on RF, running economy (RE) and perceptual responses. A between subject's case-control study design was incorporated. Eleven runners practiced three styles of Pranayama (30 min/day 6 days/week) for 3 consecutive weeks (YG) and completed a VO2 max tests on a treadmill (trial 1), basic RF tests, and constant workload RE trials at 60, 70, and 80% VO2 max (trial 2 and 3). A control group (n = 10) (CT) completed the same pre - post testing without intervention. Pre vs. post values for resting forced vital capacity (FVC), peak expiratory flow rate (PEFR) and forced expiratory flow volume in one second (FEV1). Yoga improved FVC and FEV1, but did not significantly impact RE However, RPE-L for HIGH had an interaction (p < 0.05) showing a decrease for YG and an increase for CT. The current study suggests 3 weeks of yogic Pranayama fails to significantly impact RE, however some evidence indicates YG may positively alter perceptual responses at individually prescribed workloads. More work is needed to definitively establish benefits of YG for runners.

Effects of Caffeine on Tennis Serve Accuracy.

This study examined the effects of caffeine on tennis serve accuracy. Division II tennis athletes (n = 10) completed two serve trials (double-blind, counterbalanced) following ingestion of 6 mg/kg of caffeine or matched placebo an hour prior to data collection. During each tennis serve trial, participants completed 48 non-fault serves divided into 3 sets with 2 serves per 8 different targets. Following each 2 serves per target format, participants completed a shuttle run sprint. Separate 2 (trial) × 8 (targets) repeated measures analysis of variances (ANOVAs) were used for distances from the target center "delta", and necessary tries for each of the 3 sets. A 2 (treatment) × 3 (set) repeated measures ANOVA was used for shuttle run times. While results were not significant, the treatment main effect approached significance (p = 0.07) in set 2 for the delta of distances when comparing caffeine (96.2 cm ± 19.8) versus placebo (107.1 cm ± 16.3). While there was no significance in sprint times, each sprint was consistently faster following caffeine consumption. Post-trial surveys revealed subjective responses approached significance with greater feelings of stomach distress (p = 0.08) and nervousness (p = 0.13) following caffeine and elevated feeling of fatigue (p = 0.19) following placebo. Therefore, with no impairment in serve accuracy coupled with some evidence of reduced fatigue, results suggest caffeine may benefit tennis athletes. Extending the understanding of the effects of caffeine on tennis serve accuracy and performance could benefit overall match performance, with the potential of improving the match outcome in extended playtime.

Effects of a 3-week High-Fat-Low-Carbohydrate Diet on Lipid and Glucose Profiles in Experienced, Middle-age Male Runners.

This study examined glucose and lipid marker responses following a 3-week, ad libitum low-carbohydrate-high-fat diet (LCHF; ~70% kcals from fat, <50 g/day of net carbohydrates) versus the habitual mixed macronutrient diet (HMD) of eight middle-age, trained male runners (40 ± 10 years; V̇O2peak = 49 ± 4 mL·kg-1·min-1). Blood was drawn at 0600 from an antecubital vein after an overnight fast under conditions of no exercise/heat stress (NEXH; 48 h of restriction from intense exercise) or 24-h after exercise/heat stress (EXH; 60 min run in hot conditions plus 5-km time trial) for both dietary conditions. Glucose improvement during LCHF approached but did not reach statistical significance (p = 0.07). Pre-exercise triacylglycerol did not differ between treatments but decreased > 20 mg/dL (p < 0.05) for both treatments from NEXH to EXH (HMD = 42 ± 16; LCHF = 35 ± 21 mg/dL). Main effects for diet were exhibited for HDL-C during NEXH and EXH (HMD = 48 ± 10 and 50 ± 11; LCHF = 57 ± 13 and 60 ± 13 mg/dL), and LDL-C also increased (p = 0.02) by ~20 mg/dL for LCHF at both collection points resulting in ~30 mg/dL greater total cholesterol for LCHF before and 24-h after exercise (p < 0.05). A 3-week, ad libitum LCHF did not elicit significant negative cardiovascular disease risk in male runners 30-50 years of age with healthy pre-intervention lipid and glucose marker status.

Effects of Ad libitum Low-Carbohydrate High-Fat Dieting in Middle-Age Male Runners.

PURPOSE: This study examined the effects of a 3-wk ad libitum, low-carbohydrate (<50 g·d) high-fat (~70% of calories) (LCHF) diet on markers of endurance performance in middle-age, recreationally competitive male runners. METHODS: All subjects (n = 8) after their normal high-carbohydrate (HC) diet had anthropometric measures assessed and completed five 10-min running bouts at multiple individual race paces in the heat while physiological variables, metabolic variables, and perceptual responses were recorded. After 20 min of rest, participants completed a 5-km time trial on a road course. Subjects then consumed an LCHF diet for 3 wk and returned for repeat testing. RESULTS: Body mass and seven-site skinfold thickness sum decreased by approximately 2.5 kg (P < 0.01) and 13 mm (P < 0.05) after LCHF diet. Rectal temperature was higher after the first 10 min of exercise (37.7°C ± 0.3°C vs 37.3°C ± 0.2°C) in the HC diet but did not differ at any other time with LCHF diet. Heart rate and perceptual measures did not display any consistent differences between treatments excluding thirst sensation for LCHF diet. RER and carbohydrate oxidation declined significantly, whereas fat oxidation increased after LCHF diet for every pace (P < 0.01). There was no significant difference (P = 0.25) in a 5-km time trial performance, but LCHF diet (23.45 ± 2.25 min) displayed a trend of improved performance versus HC (23.92 ± 2.57 min). CONCLUSION: Improved body composition and fat oxidation from LCHF diet potentially negate expected performance decrement from reduced carbohydrate use late in exercise for nonelite runners. An acute decrease in training capacity is expected; however, if performance improvement is not exhibited after 3 wk, diet cessation is suggested for negative responders.

Live vs. digital video disk exercise in college--aged females.

Although exercise digital video disk (DVD) sales have substantially increased over the past decade, little is known on the effectiveness of personal training vs. DVD exercises. The purpose of this study was to compare energy expenditures and heart rates of live and DVD vigorously intense exercise sessions. Twenty active and low-to-moderate fit, college-aged females completed 2 identical exercise sessions. Each exercise session consisted of 6 exercises; 1 session was completed with a personal trainer and the other with a DVD. A portable metabolic analyzer was used to measure oxygen consumption and record heart rate. Both energy expenditure (p < 0.001) and heart rate (p = 0.001) were significantly higher during the live exercise session as compared with the DVD exercise session. Rate of perceived exertion was significantly higher for the live exercise session compared with the DVD exercise session (p = 0.045). Finally, the majority (89%) of the participants reported that they preferred the live exercise session over the DVD exercise session. The results suggest that low-to-moderately fit college-aged females not only prefer exercise sessions with a personal trainer but will also demonstrate higher energy expenditures and heart rates.