Caffeine, lactic acid, or nothing: What effect does expectation have on men's performance and perceived exertion during an upper body muscular endurance task?

Objective: We tested the impact of subjects' belief in an ingested substance's ergogenic or ergolytic properties on muscular endurance performance and perceived exertion. Methods: Trained men (n = 15, age = 41 ± 4 y; body mass = 82.1 ± 15.8 kg; height = 173 ± 8 cm; experience = 7.4 ± 2.3 y) completed one set to failure at 80% repetition maximum of the bench press under three conditions. In all conditions, subjects ingested capsules of an identical, inert substance (300 mg cellulose), but, in a randomized order, subjects were told that they were either ingesting caffeine (Placebo), lactic acid (Nocebo), or cellulose (Control) and received information on the respective alleged ergogenic/ergolytic/neutral effects of each. Repetitions completed and rating of perceived exertion (RPE) were recorded. The data were analyzed among conditions using a Friedman test with post hoc analyses accomplished through Durbin-Conover tests. Spearman correlations were used to compare repetitions performed and RPE between Nocebo and Placebo conditions. Statistical significance was set at P ≤ 0.05. Results: Subjects lifted more (P < 0.001) repetitions in the Placebo condition (14.1 ± 3.0) versus Control (10.3 ± 2.9) or Nocebo (7.5 ± 2.6), while Control and Nocebo performances were similar (P = 0.192). Lower RPE was noted in Placebo versus Control (P = 0.003) and Nocebo (P < 0.001) and lower in Control versus Nocebo (P = 0.025). Subjects who performed more repetitions with Placebo tended to perform fewer repetitions under the Nocebo condition (Spearman's Rho =-0.578). Conclusion: This study believes that the ergogenic or ergolytic properties of a substance can measurably impact upper-body muscular endurance performance and RPE in trained men.

Psychological effect of acute creatine pre-workout supplementation induces performance improvement in resistance exercise.

The purpose of this study was to test whether believed versus actual acute creatine ingestion impacted resistance exercise performance. Fifteen men (21.9 ± 2.7 years old) completed four bouts of three sets each of squat and bench press to volitional fatigue at a 10RM load with 1-min between-sets rest interval. Thirty minutes prior to each exercise bout, they received the following treatments in a randomized order: 1) nothing (CON); 2) 0.3 g·kg-1 dextrose placebo (PLC); 3) 0.3 g·kg-1 dextrose, identified as creatine (Cr-False); 4) 0.3 g·kg 20 -1 creatine, identified as creatine (CrTrue). Between-treatments comparisons included the total repetitions completed and the rate of perceived exertion. Results revealed (p < 0.05) higher repetitions performed for all treatments versus CON for both squat and bench press. In the squat, more repetitions were performed with Cr-True (p < 0.001) and CrFalse (p < 0.001) than with either CON or PLC. Bayes Factor analyses revealed strong (PLC to Cr-True BF = 19.1) and very strong (PLC to CrFalse BF = 45.3) posterior probability favouring positive effects for both "creatine" conditions over PLC for the squat. In conclusion, in acute measures, belief versus ingestion of creatine yields similar exercise performance.

Salivary stress hormone response and performance in full competition after linear or undulating periodization training in elite powerlifters.

BACKGROUND: The purposes of this study were to determine differences in training loads and stress hormones among national level powerlifting competitors and the effect on performance. METHODS: Thirteen experienced male powerlifters provided detailed training logs during the 8 weeks prior to a national competition. Participants were divided into linear (LP, N.=6) and undulating periodization (UP, N.=7) training groups. Following weigh-ins and after successfully completing the competition, participants provided saliva samples. RESULTS: LP resulted in lower levels of salivary cortisol (sC) (LP 4.27±0.71 nmols/L; UP 5.53±0.78 nmols/L) and higher testosterone-to-cortisol ratio (T:C) (LP 8.03±0.84 nmols/L; UP 5.23±1.41 nmols/L) compared to UP prior to competition. Following competition, both LP and UP groups had significant increases in salivary testosterone (sT) (LP 383.70±34.96 nmols/L; UP 376.62±38.17 nmols/L) and sC (LP 17.67±1.39 nmols/L; UP 18.17±1.46 nmols/L) and significant reductions in T:C (LP 8.03±0.80 to 6.67±0.83; UP 5.23±1.41 to 4.95±1.00). Finally, the UP group had a significantly higher Wilks coefficient following the competition compared to the LP group (LP 440.7±31.83 vs. UP 480.29±24.13). CONCLUSIONS: It appears that the higher volume loads undertaken by UP have a larger perturbation on resting stress hormones; however, this does not seem to negatively influence powerlifting performance.

Influence of Exercise Time of Day on Salivary Melatonin Responses.

BACKGROUND: Sleep deprivation negatively affects cognition, pain, mood, metabolism, and immunity, which can reduce athletic performance. Melatonin facilitates sleepiness and may be affected by the proximity of exercise to sleep. PURPOSE: To evaluate the influence of exercise time of day on salivary melatonin (s-melatonin) responses. METHODS: Twelve regularly exercising men (age 20.75 [0.62] y, height 1.75 [0.04] m, mass 73.63 [10.43] kg, and maximal oxygen consumption 57.72 [6.11] mL/kg/min) participated in a randomized, crossover design. Subjects completed 3 protocols-morning exercise (09:00 h), afternoon exercise (16:00 h), and no exercise (CON)-at least 5 d apart. Exercise sessions consisted of 30 min of steady-state running at 75% of maximal oxygen consumption. Saliva was collected via passive drool at 20:00, 22:00, and 03:00 h following all sessions. RESULTS: Repeated-measures analysis of variance revealed significant time (P = .001) and condition (P = .026) effects for melatonin. Levels of s-melatonin were significantly increased at 03:00 h compared with 20:00 and 22:00 h for all conditions. Post hoc analyses revealed that s-melatonin at 22:00 h was significantly higher after morning exercise (16.5 [7.5] pg/mL) compared with afternoon exercise (13.7 [6.1] pg/mL) sessions (P = .03), whereas neither exercise condition significantly differed from the control (P > .05). CONCLUSIONS: It appears that exercising in the afternoon may blunt melatonin secretion compared with morning exercise. If sleep is an issue, morning exercise may be preferable to afternoon exercise.

Planned Load Reduction Versus Fixed Load: A Strategy to Reduce the Perception of Effort With Similar Improvements in Hypertrophy and Strength.

PURPOSE: To compare muscle thickness and 10-repetition maximum (10RM) between no load reduction and load reductions during 16 wk of resistance training. METHODS: A total of 21 moderately trained men (age 23.2 [4.2] y, body mass 75.1 [7.6] kg, height 175 [4] cm) were randomized into 1 of 3 exercise groups: control (CON, n = 7), all sets with 10RM load; 5% load reduction (RED 5, n = 7); and 10% load reduction (RED 10, n = 7) for set 2 and set 3. The resistance training program consisted of completing 3 sets each of biceps and Scott curls, performed to volitional fatigue 3 d·wk-1. RESULTS: Volume load lifted over the 16 wk was similar among groups (CON, 38,495 [4397] kg; RED 5, 37,388 [3684] kg; RED 10, 42,634 [6733] kg; P = .094). Muscle thickness increased in all groups (P < .001), with no differences noted among groups (P = .976). Biceps-curl and Scott-curl 10RM increased in all groups (P < .001), with no differences noted among groups (Scott curl P = .238; biceps curl P = .401). Rating of perceived exertion (RPE) was significantly lower for RED 10 (6.8 [0.1]) than for CON (7.0 [0.1]; P < .001) or RED 5 (7.1 [0.1]; P = .001) for the Scott curl. RPE was significantly lower (P = .001) for the biceps curl in RED 10 (6.8 [0.3]) than in CON (7.3 [0.9]), with neither group different from RED 5 (7.0 [0.1]). CONCLUSIONS: Load reduction did not yield a difference in hypertrophy or 10RM as compared with CON. However, RED 10 induced a significantly lower RPE. Thus, load reduction may be a beneficial strategy to reduce the perception of effort during training while achieving similar improvements in hypertrophy and strength.

Carbohydrate mouth rinse enhances time to exhaustion during treadmill exercise.

Mouth rinsing with a CHO solution has been suggested to improve short (<1 h) endurance performance through central effect. We examined the effects of mouth rinsing with a CHO solution on running time to exhaustion on a treadmill. Six well-trained subjects ran to exhaustion at 85% VO2max , on three separate occasions. Subjects received either an 8% CHO solution or a placebo (PLA) every 15 min to mouth rinse (MR) or a 6% CHO solution to ingest (ING). Treatments were assigned in a randomized, counterbalanced fashion, with the mouth-rinsing treatments double-blinded. Blood samples were taken to assess glucose (Glu) and lactate (Lac), as well as the perceived exertion (RPE). Gas exchange and heart rate (HR) were collected during all trials. Subjects ran longer (P = 0·038) in both the MR (2583 ± 686 s) and ING (2625 ± 804 s) trials, compared to PLA (1935 ± 809 s), covering a greater distance (MR 9685 ± 3511·62 m; ING 9855 ± 4118·62; PLA 7295 ± 3727 m). RER was significantly higher in both ING and MR versus PLA. No difference among trials was observed for other metabolic or cardiovascular variables (VO2 , Lac, Glu, HR), nor for RPE. Endurance capacity, based on time to exhaustion on a treadmill, was improved when either mouth rinsing or ingesting a CHO solution, compared to PLA.

Salivary Lymphocyte Responses Following Acute Anaerobic Exercise in a Cool Environment.

Carlson, LA, Lawrence, MA, LeCavalier, K, and Koch, AJ. Salivary lymphocyte responses following acute anaerobic exercise in a cool environment. J Strength Cond Res 31(5): 1236-1240, 2017-The purpose of this study was to examine the impact of anaerobic training on salivary lymphocytes (s-LYMPH), and further determine whether these responses differ between cool vs. thermoneutral environments. Nine lightly clothed (∼0.3 clo) volunteers (7/2 women/men: age, 21 ± 1 years; height, 168.7 ± 7.3 cm; weight, 66.4 ± 8.4 kg; body fat, 20.6 ± 7.6%) completed speed, agility, and quickness (SAQ) sessions in both warm (18.9° C; Biddeford) and cool (10.4° C; Thorsmörk) temperatures. The SAQ sessions consisted of 3 trials of 20-m sprints, 40-m sprints, t-tests, and box drills, and two 300-yd shuttle runs in both conditions. Saliva samples via passive drool were collected at baseline, immediately postexercise, and after 2 hours of recovery. The s-LYMPH increased (p < 0.001) immediately postexercise, followed by a decrease (p < 0.001) below baseline values after 2 hours of recovery in both environments. The s-LYMPH counts were lower (p < 0.001) for the cool environment than for the thermoneutral environment. The s-LYMPH counts increased postexercise, followed by a decrease after 2 hours of recovery regardless of environment. Acute anaerobic exercise induced transient changes in s-LYMPH counts similar to that observed in peripheral blood. Compared with baseline measures, changes in s-LYMPH were of a smaller magnitude after exercise in the cool environment compared with thermoneutral environment. In summary, there is no indication that exercise in the cool environment presented a greater challenge to the subjects' immunity. Rather, these data indicate exercise in a cool environment produces smaller fluctuations in salivary immune cells compared with resting levels.

Comparison of Knee Moments and Landing Patterns During a Lateral Cutting Maneuver: Shod Vs. Barefoot.

Noncontact anterior cruciate ligament (ACL) injuries often occur during lateral cutting maneuvers, in which extension, adduction, and external rotation create high loads on the ACL. The aim of this study was to examine knee moments and foot strike patterns during lateral cutting when shod (SD) and barefoot (BF). Fifteen NCAA Division III athletes (7 female and 8 male; age 20.2 ± 1.5 years; mass 71.5 ± 11.3 kg; height, 1.7 ± 0.06 m) without lower limb pathologies were analyzed during 5 trials of 45° lateral cutting maneuvers for each limb in both BF and SD conditions with the approach speed of 4.3 m·s. Kinetic and kinematic data were collected using an 8-camera motion capture system and a force plate with collection rates at 240 Hz and 2400 Hz, respectively. Paired t-tests were used to determine differences conditions. The SD condition produced a significantly (p ≤ 0.05) greater peak adduction moment and cutting, whereas BF caused more anterior foot strike. Lateral cutting when BF places no more stress on the ACL than when SD. Our findings suggest that lateral cutting maneuvers when BF will not increase stress on the ACL.

Influence of the Flo-Dynamics Movement System intervention on measures of performance in older persons.

BACKGROUND: Fall-related injuries associated with aging are a serious clinical and economic problem. The Flo-Dynamics Movement System (FDMS), which consists of eight movements with a water-filled device, may be a useful low-impact exercise suited for older persons. This study investigated the effects of the FDMS regimen with the Wun-Jo trainer on measures of strength, flexibility, and balance in older individuals. METHODS: In a quasi-experimental study, 15 healthy subjects aged 61-79 years participated in an FDMS exercise program with the Wun-Jo trainer, consisting of three weekly 30-minute sessions. The following measures were assessed pretraining and after 8 weeks of training: knee flexor and extensor isokinetic strength; grip strength; the Short Physical Performance Battery; functional reach; and low back and hamstring flexibility. Data were analyzed using repeated measures analysis of variance, with statistical significance set at the P ≤ 0.05 confidence level. RESULTS: Sit and reach test scores significantly increased (+21%) from baseline to week 8 (P < 0.001). Forward-left functional reach testing significantly increased (P = 0.012), while forward-right functional reach testing did not change (P = 0.474). Both left-lateral (P = 0.012) and right-lateral (P = 0.036) functional reach scores improved. Grip strength increased in both the left (+11.9%) and right (+14.5%) hands (P < 0.001 for each). Isokinetic knee extension at 60° per second increased for the left (+15.6%) and right (+17.6%) significantly (P = 0.001 for each). Isokinetic knee flexion at 60° per second significantly increased for both the left (+43.2%, P = 0.010) and right (+41.7%, P < 0.001). Time to complete the ten-repetition chair stand decreased significantly (-31%, P = 0.004). The 8-feet walk time also significantly decreased (-21.6%, P < 0.001). CONCLUSION: Participating in the FDMS with the Wun-Jo device may improve balance, low back and hamstring flexibility, walking speed, and knee extensor/flexor and grip strength in older individuals. FDMS training provides an alternative to traditional exercise and offers an effective strategy to increase functional ability in the elderly.

Influence of carbohydrate ingestion on salivary immunoglobulin A following resistance exercise.

BACKGROUND: Heavy exercise stresses immune function, however carbohydrate (CHO) supplementation has been shown to attenuate the decline in some measures of immune function after exercise. The purpose of the study was to investigate the impact of CHO supplementation on salivary immunoglobulin A (s-IgA) levels, interleukin 2 (IL-2), and interleukin 5 (IL-5), following an acute bout of resistance exercise (RE). METHODS: Ten resistance trained male collegiate athletes (21±2 yr; 174±6 cm, 80±11kg, 14%±4% fat) performed RE consisting of four exercises (leg press, lat pull-downs, bench press, and leg curls). Volunteers performed four sets of 10 repetitions at 65% of 1-RM, with 2 min rest between sets for all exercises. Subjects consumed either CHO beverage (1 g•kg-1 body weight) or placebo (P) prior to, during, and after RE (randomized, double blind design). Saliva and venous blood were collected pre-, post- and 90 min post-exercise. RESULTS: No change occurred in s-IgA from rest relative to osmolality or as a secretion rate (p > 0.05). IL-2 levels were unchanged by exercise in both trials (time effect p = 0.342). IL-5 was significantly (time effect p = 0.04) decreased between rest (1.55 ± 0.07 pg•ml-1) and 90 min post-exercise (0.96 ± 0 .11 pg•ml-1), with no difference between treatments (group x time effect p = 0.610). There was no time-by-treatment interaction (p < 0.05) observed between CHO and P treatments for s-IgA or IL-5. CONCLUSION: IL-5 decreases after RE, but s-IgA and IL-2 levels remain stable. CHO ingestion prior to-, during or following RE did not appear to alter salivary immune responses.

Oral creatine supplementation augments the repeated bout effect.

PURPOSE: We examined the effects of creatine supplementation on the response to repeated bouts of resistance exercise. METHODS: Young men (24.1 ± 5.2 yr) were divided into Creatine (CM, n = 9) and Placebo (PL, n = 9) groups. On day (D) 1 and D15, subjects performed four sets of bicep curls at 75% 1-RM to concentric failure. On D8-D13, subjects consumed either 20g/d creatine monohydrate or placebo. Muscle soreness and elbow joint range of motion (ROM) were assessed on D1-D5 and D15-D19. Serum creatine kinase activity (CK) was assessed on D1, D3, D5, D15, D17, and D19. RESULTS: The first exercise bout produced increases in muscle soreness and CK, and decreases in ROM in both groups (p < .001). The second bout produced lesser rises in serum CK, muscle soreness, and a lesser decrease in ROM (bout effect, p < .01 for all), with greater attenuation of these damage markers in CM than PL. CK levels on D17 were lower (+110% over D15 for CM vs. +343% for PL), muscle soreness from D15-19 was lower (-75% for CM vs. -56% for PL compared with first bout), and elbow ROM was decreased in PL, but not CM on D16 (p < .05 for all). CONCLUSIONS: Creatine supplementation provides an additive effect on blunting the rise of muscle damage markers following a repeated bout of resistance exercise. The mechanism by which creatine augments the repeated bout effect is unknown but is likely due to a combination of creatine's multifaceted functions.

Planned intensity reduction to maintain repetitions within recommended hypertrophy range.

PURPOSE: The authors tested different loading schemes for the number of repetitions completed during multiple sets of resistance exercise. METHODS: Twenty-four resistance-trained men (age 24.0 ± 4.5 y, body mass 78.3 ±10.2 kg, height 177 ± 7 cm) were tested over a 5-wk period. During week 1 a 10-repetition maximum (10RM) in the leg press was determined. During weeks 2-5 subjects completed 4 bouts of leg presses, in a randomized fashion, consisting of 4 sets with 60 s of interset rest. Set 1 of each bout was performed with 10RM, with differing intensity for sets 2-4 as follows: (1) 10RM load for all sets (CON), (2) 5% load reduction after each set (RED 5), (3) 10% load reduction after each set (RED 10), and (4) 15% load reduction after each set (RED 15). RESULTS: Significant (P < .05) decreases in repetitions completed across sets were observed in CON (sets 2, 3, and 4) and RED 5 (sets 3 and 4). Significant increases in repetitions completed across sets (2, 3, and 4) were observed in RED 10 and RED 15 (P < .05). RED 5 (8.3 ± 0.9 repetitions) and RED 10 (12.0 ± 1.1 repetitions) allowed subjects to maintain the majority (>60%) of sets in the range of 8-12 repetitions, whereas both CON and RED 15 resulted in <50% of sets in the range of 8-12 repetitions, with the majority of sets performed <8 repetitions for CON and >12 repetitions for RED 15. CONCLUSION: Reducing load 5-10% in each set should allow maintenance of 8-12RM loads for most sets of resistance exercise.

Creatine kinase activity weakly correlates to volume completed following upper body resistance exercise.

In the current study, we examined the relationship between serum creatine kinase (CK) activity following upper body resistance exercise with a 1- or 3-min rest between sets. Twenty men performed two sessions, each consisting of four sets with a 10-repetition maximum load. The results demonstrated significantly greater volume for the 3-min condition (M = 4156 kg, SD = 867, for 3 min; vs. M = 3503 kg SD = 759, for 1 min; p < .001), with no significant differences in delta CK activity between conditions (p = .574). Nevertheless, there was a weak correlation between the delta CK activity and total volume of exercise completed (r = .55 with a 1-min rest, and r = .45 with a 3-min rest). Therefore, the volume following upper body resistance exercise correlates weakly with serum CK levels, irrespective of rest interval length between sets.

Comparison of kettlebell swings and treadmill running at equivalent rating of perceived exertion values.

The purpose of this study was to compare metabolic demand of a kettlebell (KB) swing routine with treadmill (TM) running at equivalent rating of perceived exertion (RPE). Thirteen subjects (11 male, 2 female, age = 21.4 ± 2.1 years, weight = 73.0 ± 9.2 kg) completed a 10-minute KB swing routine consisting of 35-second swing intervals followed by 25-second rest intervals. Men used a 16-kg KB, and women used an 8-kg KB. After 48 hours of rest, the subjects completed a 10-minute TM run at equivalent RPEs as measured during the swing workout. Metabolic data were monitored each minute during each exercise using an automated cart, with the final 7 minutes used for analysis. The RPE and heart rate (HR) recorded at minutes 5, 7, 9, and 10 increased by 2-3 and 7-9%, respectively, for each exercise, producing a significantly increasing pattern but no significant difference between exercises. Average HR and RPE were not significantly different between KB and TM and averaged 90 and 89%, respectively, of age-predicted HRmax. Oxygen consumption, METS, pulmonary ventilation, and calorie expenditure were significantly higher for TM (25-39%) than for KB. Respiratory exchange ratio (TM = 0.94 ± 0.04, KB = 0.95 ± 0.05) and respiratory rate (TM = 38 ± 7, KB = 36 ± 4 b·min) were not significantly different between the exercises at any time point. During TM and KB exercises matched for RPE, the subjects are likely to have higher oxygen consumption, work at a higher MET level, and burn more kilocalories per minute during TM running than during KB swings. However, according to the American College of Sports Medicine standards, this KB drill could provide sufficient exercise stress to produce gains in aerobic capacity.

Impact of testing strategy on expression of upper-body work capacity and one-repetition maximum prediction after resistance training in college-aged men and women.

The purpose of this study was to assess the effect of resistance training on upper-body muscular strength and the expression of work capacity and muscular endurance. In addition, a training-induced change in the relationship between muscular strength and endurance was assessed by testing changes in the accuracy of using endurance repetitions to predict 1 repetition maximum (1RM) bench press before and after training. College-aged men (n = 85) and women (n = 62) completed a 12-week linear periodization resistance training program. Before and after training, the subjects were assessed for 1RM and repetitions to fatigue (RTFs) with a submaximal load. After pretraining 1RM determination, the subjects were randomly assigned to perform RTFs at 65% 1RM (n = 74) or 90% 1RM (n = 73). Pretraining and posttraining RTFs were conducted at the same respective % 1RM. Work capacity was determined from repetition weight × RTF. After training, there was a significant increase in 1RM in both men (∼14%) and women (∼23%). Posttraining RTF was not different from pretraining RTF at 65 %1RM (18.2 ± 5.1 and 19.0 ± 6.0, respectively) but was significantly reduced in the 90% 1RM group (6.1 ± 3.6 vs. 4.5 ± 2.7, respectively). Likewise, there was a differential effect of training on the expression of work capacity, which increased in the 65 % 1RM group (123 ± 155 kg-reps) but decreased in the 90% 1RM group (-62 ± 208 kg-reps); the effect was independent of gender within each testing group. In conclusion, the changes in muscular strength associated with resistance training produced an increase in work capacity when tested with a 65 % 1RM load without a change in endurance. In contrast, both work capacity and endurance decreased when tested with 90% 1RM. Thus, the impact of strength training on work capacity and muscle endurance is specific to the load at which endurance testing is performed.

Effect of varying rest intervals between sets of assistance exercises on creatine kinase and lactate dehydrogenase responses.

To examine the effects of different rest intervals between sets on serum creatine kinase (CK) and lactate dehydrogenase (LDH) activity, 10 men (age = 25.6 ± 2.2 years, height = 173.1 ± 7.1 cm, and body mass = 75.9 ± 10.0 kg) participated in a randomized within-subject design that involved 4 resistance exercise sessions. Each session consisted of 4 sets of 10 repetitions with 10 repetition maximum loads for the chest press, pullover, biceps curl, triceps extension, leg extension, and prone leg curl. The sessions differed only in the length of the rest interval between sets and exercises, specifically: 60, 90, 120, 180 seconds. Serum CK and LDH were significantly (p < 0.05) elevated 24-72 hours after each session, with no significant differences between rest intervals (p = 0.94 and p = 0.99, respectively). The mechanical stress imposed by the 4 resistance exercise sessions invoked similar damage to the muscle fibers independent of the rest interval between sets. These data indicate that the accumulated volume of work is the primary determinant of muscle damage in trained subjects who are accustomed to resistance exercise with short rest intervals.

Creatine kinase and lactate dehydrogenase responses after upper-body resistance exercise with different rest intervals.

The purpose of the current study was to compare serum creatine kinase (CK) and lactate dehydrogenase (LDH) concentrations at multiple time points after resistance exercise sessions that incorporated different rest intervals between sets and exercises. Twenty untrained men (18.65+/-0.49 years, 68.30+/-7.98 kg, and 174.4+/-4.80 cm) performed 2 resistance exercise sessions (i.e., 3 sets with 80% 1 repetition maximum for 5 upper-body exercises) with either 1-minute (SEQ1) or 3-minute (SEQ3) rest between sets and exercises. For each session, CK and LDH concentrations were measured before exercise (PRE) and 24, 48, and 72 hours after exercise (24P, 48P, and 72P). Subjects lifted a 24% greater (p<0.05) volume load during SEQ3 than during SEQ1. Within SEQ1, significant differences in CK concentrations were demonstrated between most time points, except between 24P and 72P. Similarly, within SEQ3, significant differences in CK concentrations were demonstrated between most time points, except between 24P and 72P and between 48P and 72P. The CK concentrations were highest at 48P for both sessions. When the CK concentrations were compared between SEQ1 and SEQ3, no significant differences were demonstrated at any time point. Within SEQ1, a significant difference in LDH concentration was demonstrated between 48P and 72P. Within SEQ3, significant differences in LDH concentrations were demonstrated between PRE and 24P and between PRE and 48P. The LDH concentrations were highest at 72P for SEQ1 and at 24P for SEQ3. When the LDH concentrations were compared between SEQ1 and SEQ3, no significant differences were demonstrated at any time point. These results suggest that muscle damage was similar between rest intervals; however, the volume load completed to induce the muscle damage was significantly greater when 3-minute rest intervals were employed. Therefore, when considered relative to the volume load completed, 1-minute rest intervals during resistance exercise may invoke greater muscle damage.

Oxygen cost of kettlebell swings.

In recent years, kettlebells have re-emerged as a popular training modality for the conditioning of athletes. We sought to quantify the aerobic challenge of one popularly recommended kettlebell workout. Ten college-aged men (age = 20.8 +/- 1.1 years, height = 179 +/- 3 cm, body mass = 77.3 +/- 7.7 kg, Vo2max = 52.78 +/- 6.22 ml.kg.min) completed a graded exercise test to exhaustion for the determination of Vo2max. Two to 7 days later, subjects completed a kettlebell exercise routine consisting of as many 2-handed swings as could be completed in 12 minutes using a 16-kg kettlebell. During this exercise bout, subjects' expired gases were collected and analyzed for the determination of Vo2, and heart rate (HR) was continuously measured. Percent HRmax and Vo2max achieved during the kettlebell exercise were compared with each other using a paired t-test. Subjects completed 265 +/- 68 swings during the 12 minutes and achieved an average Vo2 of 34.31 +/- 5.67 ml.kg.min and an average HR of 165 +/- 13 b.min. The average %HRmax (86.8 +/- 6.0%) during kettlebell exercise was significantly higher (p < 0.001) than the average Vo2max (65.3 +/- 9.8%) that was achieved. Continuous kettlebell swings can impart a metabolic challenge of sufficient intensity to increase Vo2max. Heart rate was substantially higher than Vo2 during kettlebell swings. Kettlebells provide a useful tool with which coaches may improve the cardiorespiratory fitness of their athletes. However, HRs achieved during continuous kettlebell exercise are significantly higher than actual Vo2.

Caffeine does not augment markers of muscle damage or leukocytosis following resistance exercise.

PURPOSE: The purpose of this study was to evaluate the effects of caffeine ingestion before a resistance exercise session on markers of muscle damage (CK, LDH, ALT, AST) and leukocyte levels. METHODS: Fifteen soccer athletes completed two resistance exercise sessions that differed only in the ingestion of caffeine or a placebo preworkout. RESULTS: CK concentration increased significantly following the caffeine session (415.8+/-62.8 to 542.0+/-73.5) and the placebo session (411.5+/-43.3 to 545.8+/-59.9), with no significant differences between sessions. Similarly, LDH concentration increased significantly following the caffeine session (377.5+/-18.0 to 580.5+/-36.1) and the placebo session (384.8+/-13.9 to 570.4+/-36.1), with no significant differences between sessions. Both sessions resulted in significant increases in the total leukocyte count (caffeine=6.24+/-2.08 to 8.84+/-3.41; placebo=6.36+/-2.34 to 8.77+/-3.20), neutrophils (caffeine=3.37+/-0.13 to 5.15+/-0.28; placebo=3.46+/-0.17 to 5.12+/-0.24), lymphocytes (caffeine=2.19+/-0.091 to 2.78+/-0.10; placebo=2.17+/-0.100 to 2.75+/-0.11), and monocytes (caffeine=0.53+/-0.02 to 0.72+/-0.06; placebo=0.56+/-0.03 to 0.69+/-0.04), with no significant differences between sessions. CONCLUSION: Ingestion of caffeine at 4.5 mg/kg(-1) did not augment markers of muscle damage or leukocyte levels above that which occurs through resistance exercise alone.