The Effects of Caffeine and Citrus Aurantium on Performance During Repeated Maximal Anaerobic Exercise Bouts in Habitual Caffeine Users.

ABSTRACT: McLester, CN, Bailey, P, Bechke, EE, Williamson, CM, McLester, JR, and Kliszczewicz, B. The effects of caffeine and Citrus aurantium on performance during repeated maximal anaerobic exercise bouts in habitual caffeine users. J Strength Cond Res 35(12): 3394-3399, 2021-The combination of caffeine (CAF) and Citrus aurantium (CA) have demonstrated the potential to improve various types of performance. To date, few studies have explored this relationship in purely anaerobic-based exercise. Therefore, the purpose of this study was to examine the influence of an acute dose of CAF + CA on peak anaerobic performance and the attenuation of power over multiple anaerobic bouts and to determine any differences in perceived effort or fatigue. Ten active men (25.1 ± 3.9 years) who habitually consumed caffeine volunteered to perform repeated anaerobic bouts on a cycle ergometer on 2 separate days, consuming either a placebo or 100 mg CAF + 100 mg CA. Significance was set at p ≤ 0.05 and repeated measures analysis of variance showed no main effects for peak power p = 0.520, mean power p = 0.926, minimum power p = 0.321, total work p = 0.924, time to peak power p = 0.536, or rate of fatigue p = 0.284. There was a time effect for all variables (p ≤ 0.05) with the exception of time to peak power (p = 0.181). There were no differences in any measures of perceived effort or fatigue between conditions (p ≥ 0.05), but there were time-dependent differences observed each day (p ≤ 0.05). Overall, an acute dosage of 100 mg CAF and 100 mg CA did not elicit any differences in anaerobic performance or in perceived measures of effort and fatigue in young males who habitually consume caffeine. Therefore, caution should be used when pairing CAF and CA for the goal of improving anaerobic performance, because no clear benefit was realized in this population at this dosage.

Development of a dual-energy X-ray absorptiometry-derived body volume equation in Hispanic adults for administering a four-compartment model.

The purpose of the present study was: (1) to develop a new dual-energy X-ray absorptiometry (DXA)-derived body volume (BV) equation with the GE-Lunar prodigy while utilising underwater weighing (UWW) as a criterion and (2) to cross-validate the novel DXA-derived BV equation (4C-DXANickerson), Wilson DXA-derived BV equation (4C-DXAWilson) and air displacement plethysmography (ADP)-derived BV (4C-ADP) in Hispanic adults. A total of 191 Hispanic adults (18-45 years) participated in the present study. The development sample consisted of 120 females and males (50 % females), whereas the cross-validation sample comprised of forty-one females and thirty males (n 71). Criterion body fat percentage (BF %) and fat-free mass (FFM) were determined using a four-compartment (4C) model with UWW as a criterion for BV (4C-UWW). 4C-DXANickerson, 4C-DXAWilson and 4C-ADP were compared against 4C-UWW in the cross-validation sample. 4C-DXANickerson, 4C-DXAWilson and 4C-ADP all produced similar validity statistics when compared with 4C-UWW in Hispanic males (all P > 0·05). 4C-DXANickerson also yielded similar BF % and FFM values as 4C-UWW when evaluating the mean differences (constant error (CE)) in Hispanic females (CE = -0·79 % and 0·38 kg; P = 0·060 and 0·174, respectively). However, 4C-DXAWilson produced significantly different BF % and FFM values (CE = 3·22 % and -2·20 kg, respectively; both P < 0·001). Additionally, 4C-DXAWilson yielded significant proportional bias when estimating BF % (P < 0·001), whereas 4C-ADP produced significant proportional bias for BF % and FFM (both P < 0·05) when evaluated in Hispanic females. The present study findings demonstrate that 4C-DXANickerson is a valid measure of BV in Hispanics and is recommended for use in clinics, where DXA is the main body composition assessment technique.

Agreement Between 2 Segmental Bioimpedance Devices, BOD POD, and DXA in Obese Adults.

This study examined the agreement between 2 segmental bioimpedance analysis (BIA) devices, air displacement plethysmography (BOD POD), and dual energy X-ray absorptiometry (DXA) for estimating body composition in obese adults. Fifty obese adults (25 men and 25 women; age = 34.20 ± 11.19 years; BMI = 36.14 ± 5.33 kg/m2) had their body fat percentage (BF%) and fat-free mass (FFM) evaluated with 2 segmental BIA devices (InBody 230 and InBody 720), BOD POD, and DXA (Lunar iDXA). Body composition via the BOD POD was determined using the Siri equation whereas manufacturer-based equations generated metrics (ie, BF% and FFM) for the InBody devices. The effect size of the mean differences for all BF% and FFM comparisons were trivial (Cohen's d < 0.20). The standard error of estimate (SEE), total error (TE), and 95% limits of agreement (LOAs) were low for both segmental BIA devices when compared to DXA (SEE < 2.26% and 2.35 kg; TE < 2.58% and 2.66 kg; 95% LOAs < ± 4.94% and 4.86kg). The error for BOD POD was also low when compared to DXA (SEE = 2.39% and 2.57 kg; TE = 2.34% and 2.56 kg; 95% LOAs = 4.63% and 5.06 kg). Validity statistics were slightly higher, but considered acceptable, when comparing the segmental BIA devices against BOD POD (SEE < 3.37% and 3.63 kg; TE < 3.44% and 3.79 kg; 95% LOAs < ± 6.62% and 7.19 kg). Lastly, the 2 segmental BIA devices produced nearly identical validity statistics when compared to each other. However, both BIA devices revealed proportional bias for BF% and FFM when compared to the BOD POD and DXA (all p < 0.05). The current study's findings indicate the InBody 230 is interchangeable with the InBody 720 in obese adults. Also, the trivial effect size, when compared against the BOD POD and DXA, suggest the InBody devices could be used for estimating group BF% and FFM. In contrast, the significant proportional bias demonstrates the BIA devices are not acceptable for individual estimates of body composition in an obese clinical population.

Reliability and Agreement of Various InBody Body Composition Analyzers as Compared to Dual-Energy X-Ray Absorptiometry in Healthy Men and Women.

BACKGROUND: Bioelectrical impedance analysis has evolved over the years to include the use of multiple frequencies and impedance measurements to improve the accuracy and reliability of body composition estimates. The purpose of this investigation was to evaluate the reliability of the InBody230, InBody720, and InBody770 to measure body fat percent (BF%), fat mass (FM), and fat-free mass (FFM) in the general population and to compare results to dual-energy X-ray absorptiometry (DXA). METHODS: A total of 31 males and 36 females participated in 2 d of testing separated by 24-72 h. Each visit consisted of a DXA scan, and analysis with the InBody230, InBody720, and InBody770. RESULTS: All 3 bioelectrical impedance devices (InBody230, InBody720, and InBody770) were reliable in men and women as indicated by high intraclass correlation coefficients for BF% (≥0.98), FM (≥0.98), and FFM (≥0.99) and low standard error of measurement for BF% (0.77%-0.99%), FM (0.54-0.87 kg), and FFM (0.58-0.84 kg) and minimum difference for BF% (2.12%-2.73%), FM (1.49-2.39 kg), and FFM (1.60-2.32 kg), respectively. When examining the agreement between the 3 InBody analyzers with DXA, systematic bias (underestimation of BF% and FM and overestimation of FFM) was present for all comparisons (p < 0.05) while proportional bias was present for FM in women and FFM in men. However, there was small individual error for all comparisons as indicated by the standard error of estimate and 95% limits of agreement. CONCLUSION: The InBody analyzers produce small individual error, which suggest these methods can be used as a surrogate when DXA is not available; however, practitioners should be aware of the systematic bias for all comparisons and proportional bias for FM in women and FFM in men. Furthermore, findings revealed that the research grade models, InBody720 and InBody770, added minimal benefit over the portable InBody230 when assessing BF%, FM, and FFM.

Comparison of Muscle Activation Between Back Squats and Belt Squats.

Evans, TW, McLester, CN, Howard, JS, McLester, JR, and Calloway, JP. Comparison of muscle activation between back squats and belt squats. J Strength Cond Res 33(7S): S52-S59, 2019-A machine belt squat is a piece of equipment designed to allow the performance of squats while loading weight on the lifter's hips using a belt. The purpose of this investigation was to determine whether belt squats differ from back squats in activation of the primary movers and to determine the predictive capabilities of back squat load, training status, and anthropometric data on belt squat load. Thirty-one participants (16 men and 15 women) completed anthropometric measurements, a demographic questionnaire, a familiarization visit, and 2 testing visits, completing a 5 repetition maximum test for back squat and belt squat. Surface electromyography was used to measure muscle activation for the left and right vastus medialis, vastus lateralis, rectus femoris, and gluteus maximus (GM). Comparison of muscle activation between the 2 exercises showed significant differences in the left GM (back squat: 0.84 ± 0.45, belt squat: 0.69 ± 0.22, p = 0.015) and right GM (back squat: 0.86 ± 0.45, belt squat: 0.71 ± 0.29, p = 0.004). Regression analysis computed significant prediction equations for belt squat load for general population, men, women, and advanced lifters. Overall, results indicate that belt squats may significantly differ in GM activation from back squats. Back squat load, as well as other variables, may be effective in accurately estimating appropriate belt squat load. These findings may help to more appropriately program for training with machine belt squats as a back squat alternative.

A Comparison of Anaerobic Power Tests using Cycle Ergometry and Nonmotorized Treadmill Ergometry at Optimized Loads.

The purpose of this study was to compare performance markers derived from a 30-second maximal bout on a cycle ergometer (CE) and non-motorized treadmill (NMT) under optimized loads. Recreationally active participants (n = 40) volunteered for the study. Force-velocity tests on the CE and NMT were used to determine optimal resistance for peak power (PP) production. The remaining visits were randomized and counterbalanced, with a single 30-second maximal test on CE or NMT to assess PP, mean power (MP), fatigue index (FI), over the course of the 30-second test, and maximum heart rate (HRmax) and blood lactate (BLa-) taken 1-minute post. Results were that PP and MP were higher (P<0.05) on CE compared to NMT for both sexes. FI did not differ among males (P=0.201) whereas females showed higher FI (P=0.002) on the CE. HRmax and BLa- were higher (P<0.05) after NMT for both sexes. There was no difference for optimal braking force on NMT between males (16.65±4.49%BW) and females (14.30±3.10%BW) (P=0.061). CE optimal torque factor was higher for males (0.78±0.16 Nm/kg) compared to females (0.62±0.14 Nm/kg) (P=0.001). Overall, CE produced higher power output using optimized loads in recreationally active males and females, while NMT test resulted in a higher HRmax and BLa- concentration. These tests for anaerobic power, when performed with optimized loads, produced different results for several variables, therefore these modalities should not be considered interchangeable. Practitioners should consider which modality best mimics the activities of the person being tested when selecting a protocol.

Specificity of training modalities on upper-body one repetition maximum performance: free weights vs. hammer strength equipment.

The purpose of this study was to determine whether a relationship exists between 1-repetition maximum (1RM) performed on hammer strength (HS) machines compared to free weights (FWs) and also to develop regression equations that can accurately predict 1RM when switching from exercise modality to another. Thirty-one trained male subjects performed 1-RM lifts (1RM's) on 3 HS externally loaded machines and 3 comparable FW exercises. Subjects performed 2 1RM tests during each laboratory session, with at least 48-72 hours of recovery between each. One repetition maximum data were used to (a) determine the relationship between 1RM performed on HS vs. FW and (b) to develop regression equations that can accurately predict 1RM's when switching from 1 exercise modality to another. Statistics revealed significant differences (p < 0.05) between 1RM's performed on the HS equipment as compared to its corresponding (FW) exercise. For all exercises, 1RM's were significantly greater on the HS equipment. Regression equations were developed for all exercises, except when predicting the HS shoulder press and the HS preacher curls from their free weight counterparts, where no variables existed that could significantly predict their respective 1RM's. As 1 RMs were significantly greater when using the HS equipment compared to when using FWs, those transitioning from HS exercise to FW exercise should exercise caution.

Relative accuracy of anthropometric-based body fat equations in males and females with varying BMI classifications.

BACKGROUND: BMI based body fat equations developed from Womersley and Durnin (BMIWO), Jackson et al. (BMIJA), Deurenberg et al. (BMIDE), and Gallagher et al. (BMIGA) are commonly used to quantify body fat percentage (BF%). However, relative fat mass (RFM) is a new anthropometric-based method that has been proposed as an alternative. AIMS: The purpose of this study was to examine the independent and interactive effects of sex and BMI classification on the relative accuracy of BMI-based body fat equations and RFM. METHODS: Males (n = 75) and females (n = 75) were stratified and classified into three different groups; 1) normal weight (n = 50 [NW: 50% males]; BMI<25.0 kg/m2); 2) overweight (n = 50 [OW: 50% males]; BMI≥25.0-29.9 kg/m2); 3) obese (n = 50 [OB: 50% males]; BMI≥30.0 kg/m2). A criterion three-compartment model (3C model) was determined with air displacement plethysmography for body volume and multi-frequency bioimpedance analysis for total body water. Data were stratified by sex and BMI classification. Difference scores were created by subtracting estimated BF% from 3C model BF%. RESULTS: A significant SEX × BMI interaction was detected for all comparisons (all p < 0.05). Post hoc analysis indicated the differences in BF% were statistically significant between OW females and males for all equations (BMIWO:-2.99 ± 4.79% vs. 4.71 ± 5.86%, p = 0.003; BMIJA:-1.77 ± 4.83% vs. 5.77 ± 5.85%, p < 0.001; BMIDE:-3.09 ± 4.80% vs. 4.97 ± 5.98%, p < 0.001; BMIGA:0.36 ± 4.51% vs. 4.56 ± 5.55%, p = 0.018; RFM:-2.17 ± 4.84% vs. 3.01 ± 5.34%, p = 0.004, respectively). In addition, there were significant differences between females and males classified as NW (BMIJA:-2.11 ± 4.15% vs. 2.61 ± 5.98%, p = 0.008) and OB (BMIGA:2.40 ± 3.36% vs. -1.09 ± 6.40%, p = 0.006). CONCLUSIONS: The current findings highlight that RFM does not appear to overcome error commonly associated with BMI-based body fat equations when stratifying by sex and BMI classification. Nonetheless, practitioners can use BMIWO, BMIDE, and RFM in males and females classified as NW or OB, but should employ caution prior to use in OW persons.

Acute heart rate, blood pressure, and RPE responses during super slow vs. traditional machine resistance training protocols using small muscle group exercises.

Acute cardiovascular and perceptual responses to Super Slow resistance training (SS) are not well understood. This study compared blood pressure (BP), heart rate (HR), and ratings of perceived exertion (RPE) between SS and traditional machine (TM) protocols. Participants (n = 20) completed three sessions of elbow flexion (EF) and knee extension (KE). Session 1 consisted of determining 1RM for EF and KE and a familiarization trial for the SS technique. Sessions 2 and 3 were counterbalanced, with subjects completing three sets of SS (10 seconds concentric, 5 seconds eccentric per rep, 40% 1RM) and TM (2 seconds concentric, 4 seconds eccentric per rep, 65% 1RM). Paramount resistance training equipment was used for both exercises. Peak HR was recorded for each set, with recovery HR taken between sets after 3 minutes of rest. Blood pressure was taken after 5 minutes of seated rest, after each set, before sets 2 and 3, and at 2 minutes post set 3. Ratings of perceived exertion for active musculature were obtained three times per set. Although systolic BP (SBP) and diastolic BP (DBP) responses were not significantly different between SS and TM for EF or KE, SBP (SS and TM combined) was significantly lower during EF and was significantly higher during KE than resting BP. Diastolic BP (SS and TM combined) was not significantly different from resting BP for EF or KE. Peak HR was significantly greater during TM (vs. SS) for EF and KE. Ratings of perceived exertion were also significantly greater during TM for EF and KE. Even though SBP was greater for SS and TM combined during KE, comparing SS and TM revealed minimal differences in BP. This suggests that, when performing small muscle group exercises with lighter weight at a slow speed, either SS or TM would be appropriate for individuals to whom strength training is not contraindicated.

An Investigation of the Differences between Perceived vs. Measured Body Composition, Social Physique Anxiety, and Overall Appearance Satisfaction among College Students.

The purpose of this study was to examine the differences between body composition, social physique anxiety (SPA) and appearance satisfaction among college students by sex and BMI. A secondary purpose was to assess levels of appearance satisfaction before and after body composition testing and discover any differences between perceived body fat percentage (BF%) and weight versus actual measurements. Participants included 212 college students (93 males, 119 females), 22.0 ± 2.2 years. They answered a demographic questionnaire, the Social Physique Anxiety Scale (SPAS), post-assessment questions, and underwent body composition testing via dual energy x-ray absorptiometry (DXA). There was a significant correlation between measured BF% and SPAS scores (r = 0.531, P < 0.001). Males scored lower on the SPAS compared to females (25.3 ± 9.4 vs. 33.1 ± 9.1, P < 0.001). The sample underestimated BF% with females underestimating by more than males, 5.7 ± 7.3% vs. 3.7 ± 5.4%, P = 0.036. There was no difference between perceived and measured weight for women (P = 0.500) however, males overestimated their weight (P = 0.004). There was a difference in appearance satisfaction pre and post body composition for females (pre = 4.4 ± 1.7, post = 4.2 ± 1.9, P = 0.026) but not for males (pre = 5.3 ± 1.5, post = 5.0 ± 1.8, P = 0.063). Overall, males had lower levels of SPA and higher levels of appearance satisfaction than females and knowledge of BF% negatively affected appearance satisfaction scores for females. Finally, both males and females underestimated BF% compared to DXA.

An investigation of the accuracy and reliability of body composition assessed with a handheld electrical impedance myography device.

The purpose of this study was to compare the body fat per cent (BF%) assessed with a unique handheld electrical impedance myography (EIM) device, along with other popular methods, to dual-energy X-ray absorptiometry (DXA). Participants included 33 males (aged 24.3 ± 4.6 years) and 38 females (aged 25.3 ± 8.9 years) who completed 2 visits separated by 24-72 h. The assessments included DXA, bioelectrical impedance analysis (BIA), skinfold measures (SKF), and three separate EIM measurements. No significant differences in BF% (P > 0.05) were found between all EIM assessments when compared against DXA for both males and females for each visit. All methods showed no significant differences in BF% (P > 0.05) between days within themselves. Across both days, the standard error of the estimate (SEE) for the EIM measurements ranged from 2.66% to 3.15%, the SEE for BIA was 2.80 and 2.85, and for SKF was 2.90 and 2.82. The 95% limits of agreement ranged from ±5.34% to ±6.38% for EIM measurements and were highest for SKF (±7.42% and ±7.47%). The total error for both days was largest for SKF (5.20% and 5.35%) and lowest for the EIM measurements (2.48-3.24%). This investigation supports use of a handheld EIM device as an accurate and reliable method of estimating BF% compared to DXA in young, apparently healthy individuals with BF% in the range of 10-22% for males and 20-32% in females and suggests this EIM device be considered a viable alternative to other established field measurements in this population.

Central Hemodynamics Measured During 5 Repetition Maximum Free Weight Resistance Exercise.

The PhysioFlow™ is a piece of equipment that uses bioimpedance cardiography to measure central hemodynamics. The purpose of this research was to explore the novel approach of monitoring central hemodynamics during free weight resistance exercise using bioimpedance cardiography throughout a 5 repetition maximum (5RM). Thirty participants ranging from beginner to advanced lifters (16 males and 14 females) completed a 5RM for back squat, seated push press, and bicep curl while connected to the PhysioFlow™ to assess the response of heart rate (HR), stroke volume (SV), cardiac output (Q), and ejection fraction (EF). Participants were cued for form and to breathe normally throughout the lifts. The PhysioFlow™ detected an increase in HR and Q for all lifts between rest and each repetition (p < 0.05). There was also an increase in HR and Q from repetition 1 to repetition 5 for all lifts (p < 0.05). No changes in EF or SV were detected between resting measurements and each repetition for all lifts (p > 0.05) and no changes in EF or SV were detected when all repetitions were compared to each other for all lifts (p > 0.05). In conclusion, the PhysioFlow™ was able to detect changes in HR and Q during dynamic free weight resistance exercise. This novel approach may provide a mechanism for monitoring central hemodynamics during free weight resistance training. However, more research needs to be conducted as the exercise protocol for this investigation did not allow for a comparison to a reference method.

Validity of DXA body volume equations in a four-compartment model for adults with varying body mass index and waist circumference classifications.

The purpose of this investigation was to determine the validity of 4-compartment (4C) model body fat percent (BF%) estimates when using dual energy x-ray absorptiometry (DXA) derived body volume (BV) equations (4C-DXA1 and 4C-DXA2) in adults with varying body mass index (BMI) and waist circumference (WC) classifications. Each model was compared to a criterion 4C model with air-displacement plethysmography (ADP) generated BV (4C-ADP). Participants were categorized as normal weight (n = 40; NW = BMI<25.0kg/m2); overweight (n = 40; OWBMI = BMI≥25.0 kg/m2); and overweight with at-risk WC (n = 35; OWBMI+WC = BMI≥25.0 kg/m2 and WC≥88.0cm for women and 102.0cm for men). 4C-DXA1 produced lower BF% than that derived using the 4C-ADP in NW (CE = -3.0%; p<0.001) while 4C-DXA2 was significantly higher (CE = 4.8%; p<0.001). The SEE and 95% limits of agreement (LOA) were lower for 4C-DXA2 (1.24% and ±2.5%, respectively) than 4C-DXA1 (2.59% and ±5.0%, respectively) and proportional bias was present for both (p<0.05). 4C-DXA1 BF% was not significant in OWBMI (CE = -0.5%; p = 0.112) whereas 4C-DXA2 was higher (CE = 4.5%; p<0.001). The SEE and 95% LOA were lower for 4C-DXA2 (1.20% and ±2.9%, respectively) than 4C-DXA1 (1.92% and ±3.9%, respectively) in OWBMI. Proportional bias was present for 4C-DXA1 (p = 0.007), but not 4C-DXA2 (p = 0.832). 4C-DXA1 and 4C-DXA2 produced significantly higher BF% in OWBMI+WC (CE = 2.2 and 2.3%, respectively; both p<0.001). The SEE and 95% LOA remained lower for 4C-DXA2 (1.15% and ±2.5%, respectively) than 4C-DXA1 (1.84% and ±3.8%, respectively). There was proportional bias for 4C-DXA2 (p = 0.020), but not 4C-DXA1 (p = 0.183) in OWBMI+WC. Only one prediction model (i.e., 4C-DXA1 in OWBMI+WC) revealed valid estimates of BF%. Practitioners are encouraged to use criteria for both BMI and WC when utilizing DXA-derived BV in 4C-models for normal and overweight populations.

A Comparison of Body Composition Across Two Phases of the Menstrual Cycle Utilizing Dual-Energy X-Ray Absorptiometry, Air Displacement Plethysmography, and Bioelectrical Impedance Analysis.

The purpose of this investigation was to utilize several different technologies to compare body composition results across two phases of the menstrual cycle, and to investigate whether being on hormonal birth control or not has any effect on results. The secondary purpose was to determine if body satisfaction or perception of fluid retention differed across phases or between groups. A total of 39 females with a mean age of 26 ± 7 yrs were included in the study, 15 were on hormonal birth control (BC) and 24 were not (non-BC). Participants came into the lab for two trials: once while menstruating and another during the estimated pre-ovulation phase of the menstrual cycle. Demographic and body satisfaction questionnaires were completed prior to body composition testing. This testing included dual-energy x-ray absorptiometry, BOD POD®, and three separate bioelectrical impedance analyses. Participants completed the body satisfaction questionnaire and all body composition tests on each trial. No significant differences (P > 0.05) were found between body fat percentage or total body water estimates taken during menses and pre-ovulation for the BC or non-BC group. There was no significant difference (P > 0.05) in overall body satisfaction across the two phases for the non-BC group, though the BC group had significantly lower body satisfaction during menses (P < 0.01). Participants in both groups identified feeling more bloated during menses (P < 0.001). Results suggest that menses should not affect the reliability of body composition estimates regardless of whether or not females are on hormonal BC.

RPE association with lactate and heart rate during high-intensity interval cycling.

PURPOSE: Physiological and perceptual measures during interval exercise are not well understood. The current study therefore examined the correspondence between RPE, HR, and blood lactate concentration ([La]) during interval cycling. METHODS: VO2peak and the 4.0 mmol x L(-1) lactate threshold were determined. In session 2, subjects (N = 12) warmed up (10 min, 0 W) and completed five 2-min intervals (INT) at >4 mmol x L(-1) workload, each separated by 3 min of recovery (REC) (60 rpm, 0 W). HR, RPE, and [La] were recorded at 10 min, at the conclusion of each INT, and each REC and 5- and 10-min recovery. RESULTS: Repeated-measures ANOVA showed [La], HR, and RPE increased significantly across time (INT and REC). At each time point, repeated-measures ANOVA was used to compare standardized data (alpha = 0.05). RPE (at INT) intensified concurrently with HR and [La] at INT. Correlations were significant for INT (P < or = 0.05) (HR-RPE: r = 0.63, [La]-RPE: r = 0.43). Similarly, RPE and HR for REC systematically increased with [La]. Correlations for REC were also significant (HR-RPE: r = 0.44, [La]-RPE: r = 0.34). Correlations were also significant for INT and REC combined (HR-RPE: r = 0.70, [La]-RPE: r = 0.22). CONCLUSIONS: INT and REC independently showed moderate correspondence for RPE-[La] and RPE-HR. However, tighter overall coupling of HR with RPE (vs [La] with RPE) and a dissociation between RPE-[La] suggest RPE during intervals of intense cycling were more sensitive to acute metabolic demand (evidenced by HR) versus [La].

A comparison of motivational factors and barriers to physical activity among traditional versus nontraditional college students.

OBJECTIVE: To investigate the motivational factors and the barriers to physical activity (PA) in traditional college students (TS) and nontraditional college students (NTS) and determine if differences exist between these 2 groups. PARTICIPANTS: A total of 746 college students; 628 were TS (19.1 ± 1.2 years), and 118 were NTS (31.2 ± 8.6 years). METHODS: In fall 2010, students voluntarily completed a demographic questionnaire, Barriers to Being Active Quiz, and Exercise Motivations Inventory-2 (EMI-2). RESULTS: EMI-2 revealed that TS and NTS differed on 8 of the 14 motivational factors for exercise. There was a significant difference between TS and NTS for the following barriers: fear of injury (p = .001), lack of resources (p = .017), and lack of skill (p = .003). CONCLUSION: Based on these findings, interventions can be developed for the varied needs of a diverse student population as it pertains to PA participation.

Effects of caffeine on repetitions to failure and ratings of perceived exertion during resistance training.

CONTEXT: Ergogenic effects of caffeine on aerobic or endurance exercise are well documented. Conversely, the ergogenic value of caffeine on high-intensity, primarily anaerobic performance is not well understood even though the proposed mechanisms of action for caffeine permit a strong theoretical basis for application to this type of exercise. PURPOSE: This study examined effects of caffeine (Ca) on number repetitions (reps), ratings of perceived exertion (RPE), and peak heart rate (PHR) during resistance-training exercise with reps performed to volitional failure. METHODS: Subjects (N = 17) were tested for 10-rep maximum in bench press (BP) and leg press (LP). In sessions 2 and 3, Ca (approximately 6 mg/kg) or placebo (Pl) was ingested 1 hr beforehand in a double-blind manner and counterbalanced order. Subjects performed 3 sets to failure (BP and LP) with reps, PHR, and RPE recorded each set. Repeated-measures ANOVAs, 2 (trial) x 3 (set), were used to analyze dependent measures with the Tukey honestly significant difference used when necessary as the post hoc test. RESULTS: In BP, no significant differences (Ca vs Pl) were observed (reps, RPE, PHR). During set 3 of LP training, Ca was associated with significantly higher reps (12.5 +/- 4.2 vs 9.9 +/- 2.6) and PHR (158.5 +/- 11.9 vs 151.8 +/- 13.2). No significant RPE differences were found during LP. CONCLUSIONS: The findings of similar RPE concurrent with higher reps suggest that caffeine can blunt pain responses, possibly delaying fatigue in high-intensity resistance training. Ergogenic effects might be limited to the later sets in a resistance-training session. Further research is warranted regarding ergogenic effects of caffeine during resistance training and potential mechanisms of action.

Effects of standing vs. seated posture on repeated Wingate performance.

Standing during cycling may increase overall muscular activity. However, effects of standing vs. seated posture on performance measures during repeated bouts have not been extensively explored. The purpose of this study was to examine the effects of standing vs. seated posture on repeated Wingate performance. Healthy volunteers (n = 35) performed 3 consecutive Wingate anaerobic power tests (W(1), W(2), W(3)) in a standing (STA) as well as seated (SIT) posture. Within-group comparisons were made for peak power, mean power, minimum power, and fatigue index. Results were considered significant at p < or = 0.05. No significant differences were found for peak power in W(1), W(2), or W(3). No significant difference was found for mean power in W(1) or W(2), but significant differences were found for mean power in W(3) (STA: 451.5 +/- 105.3, SIT: 425.7 +/- 110.0); minimum power in W(1) (STA: 433.6 +/- 100.8, SIT: 381.5 +/- 96.9), W(2) (STA: 348.1 +/- 112.9, SIT: 308.0 +/- 95.8), W(3) (STA: 292.0 +/- 103.6, SIT: 265.3 +/- 90.8); and fatigue index: W(1) (STA: 51.3 +/- 10.7, SIT: 56.9 +/- 9.3), W(2) (STA: 56.5 +/- 12.6, SIT: 61.8 +/- 12.2), W(3) (STA: 59.4 +/- 13.1, SIT: 63.6 +/- 12.4). Results suggest that a standing posture enhances performance during repeated Wingate cycling. The enhancement is most likely due to an attenuated loss in power, which in turn improves fatigue index.

A series of studies--a practical protocol for testing muscular endurance recovery.

The purpose of this series of studies was to use a practical measure to examine the course of muscular endurance recovery after 3 sets to failure in 10 men (ages 18 to 30 years) and then compare those results with 10 men (ages 18 to 30 years) who performed 7 sets and 10 older men (ages 50 to 65 years) who performed 3 sets. Recovery as indicated by number of repetitions performed was observed at 24, 48, 72, and 96 hours. Repeated-measures ANOVA was used to investigate differences in recovery over time. For group means, performance was significantly lower in all 3 groups after 24 hours (p < 0.05). At 48 hours, performance of the groups was not significantly different from baseline (p > 0.05). Number of repetitions performed at 72 hours was significantly higher than that in session 1 (10.2 +/- 1.4 reps in session 1 vs. 11.2 +/- 2.3 at 72 hours, p = 0.022) in the young 3-sets group, but not in the other groups. After 96 hours, only the young 7-sets group was found to be performing at a level approaching significance (10.3 +/- 1.2 reps in session 1 vs. 11.1 +/- 2.0 at 96 hours, p = 0.051). No significant difference was found between the young 3-sets and 7-sets groups at any time (p > 0.05). The young 3-sets group was found to be performing at a significantly higher level than the older group at 72 hours (11.2 +/- 2.3 reps in the younger vs. 9.9 +/- 1.7 in the older group, p = 0.008), a difference that also approached significance at 96 hours (p = 0.06). Large intersubject variability was observed at all time points. The results suggest that individual recovery testing before exercise prescription is practical, and this protocol may be sensitive to differences in training volume and subject age.