Copyright @ 200 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited. 9 measures (i.e., RT, response accuracy) during a modified Sternberg task administered before the start of, immediately after, and 30 min after each of the exercise interventions (i.e., resistance exercise, aerobic exercise) and the control condition (i.e., seated rest). It was hypothesized that task performance indices of working memory would be facili- tated by both acute exercise modalities. That is, shorter RT latency and increased response accuracy would be observed after both the aerobic and the resistance exercise interven- tions, relative to seated rest, with improved performance during trials necessitating greater amounts of working memory. Such a pattern of results would provide additional evidence for the disproportionately larger effect of acute exercise on tasks requiring greater amounts of executive control. METHODS Participants Twenty-one undergraduate students (nine females, age = 20.2 T 0.3 yr) from the University of Illinois at Urbana- Champaign served as participants. All participants provided written informed consent that was approved by the Institutional Review Board of the University of Illinois at Urbana-Champaign and completed the Physical Activity Readiness Questionnaire (PAR-Q), a questionnaire designed to provide sufficient preactivity screening to detect potential risk factors that might be exacerbated by acute exercise participation. Additionally, participants completed a health history and demographics questionnaire, reported being free from any neurological diseases, and reported normal or corrected-to-normal vision based on the minimal 20/20 standard. Table 1 presents participant demographics. Working Memory Task A modified Sternberg (33) task was used, which required participants to encode a memory set containing an array of three, five, or seven letters and decide whether a single probe letter was present in the encoded array. The memory sets were comprised of all capitalized consonants and contained no alphabetical consonant strings (i.e., JKLMN), whereas the probe letters were lowercase consonants, bilaterally flanked by one, two, or three ������?������ to match the memory set in physical size and visual content. A right thumb press indicated that the probe was present, and a left thumb press indicated that the probe was absent from the encoded letter array. Probes presence/absence occurred with equal probability, and participants were instructed to respond to the probe letters as quickly and accurately as possible. One block of 102 trials counterbalanced with 34 trials in each set size was presented focally on a computer monitor at a distance of 1 m, with participants being instructed to respond as quickly but as accurately as possible. All stimuli were 7-cm tall white letters presented on a black background for 2000 ms (encoded array) and 200 ms (probe letter), with a 1500-ms response window. A randomized, interstimulus interval of 2000, 2500, or 3000 ms was used throughout the task block with a 1700-ms intertrial interval. Cardiorespiratory Fitness Assessment Maximal aerobic power (VO2max) �� was measured using a motor-driven treadmill and a modified Balke protocol (1), which involved walking/running on a treadmill at a constant speed with increasing grade increments of 2% every 2 min until volitional exhaustion occurred. A com- puterized indirect calorimetry system (K4b2 COSMED, Rome, Italy) collected breath-by-breath values for oxygen consumption. A Polar HR monitor (Model A1 Polar Electro, Kempele, Finland) measured HR throughout the test, and a rating of perceived exertion (RPE) (3) was taken at the end of every 2-min stage. Relative peak oxygen con- sumption was expressed in milliliters per kilogram per minute and was based on a maximal effort when the par- ticipants achieved two of the following four criteria: no change in HR with an increase in exercise workload/ intensity a RPE Q17 a respiratory exchange ratio Q1.15 or a plateau in oxygen consumption corresponding to an increase of less than 150 mL in oxygen uptake despite an increase in workload (22). Procedure Day 1���baseline testing. On the first laboratory visit, participants completed an informed consent and the PAR-Q to screen for any previous health issues that may be exacerbated by acute exercise. Participants were then fitted with a Polar HR monitor (Model A1 Polar Electro) and had their height and weight measured using a stadiometer (to the nearest 0.5 cm) and a beam balance platform scale, respectively. A fitness assessment was then conducted, including a cardiorespiratory fitness test (VO2max) �� and strength tests to measure 1-repetition maximum (1RM) on seven exercises (triceps press, bicep curls, bench press, lat pulls, military press, single leg curl [dominate leg], and TABLE 1. Participant demographics and fitness values (T1 SE). Measure All Males Females N 21 12 9 Age (yr) 20.2 T 0.3 20.3 T 0.4 20.1 T 0.6 BMI (kgImj2) 22.9 T 0.7 22.4 T 0.6 23.6 T 1.3 RPEmax 17.9 T 0.2 18.0 T 0.3 17.8 T 0.2 HRmax (bpm) 193.4 T 1.5 192.6 T 2.3 194.6 T 1.7 VO2max �� (mLIkgj1Iminj1) 54.6 T 2.3 60.1 T 2.6 47.3 T 2.5 Triceps press max (lb) 63.6 T 4.9 79.2 T 4.1 42.8 T 3.9 Bicep curl max (lb) 57.9 T 4.7 73.3 T 3.7 37.2 T 3.2 Bench press max (lb) 144.1 T 13.6 187.1 T 12.1 86.7 T 9.3 Lat pull max (lb) 123.3 T 7.6 148.8 T 5.1 89.4 T 6.4 Military press max (lb) 78.3 T 7.9 102.1 T 8.0 46.7 T 5.0 Leg curl max (lb) 46.2 T 3.4 54.2 T 4.2 35.6 T 3.1 Leg press max (lb) 153.8 T 9.0 168.3 T 10.5 134.4 T 13.9 BMI, body mass index RPEmax, maximum ratings of perceived exertion at the comple- tion of the cardiorespiratory fitness assessment HRmax, maximum HR at the comple- tion of the cardiorespiratory fitness assessment VO2max, �� maximum oxygen consumption at the completion of the cardiorespiratory fitness assessment. APPLIED SCIENCES RESISTANCE EXERCISE AND WORKING MEMORY Medicine & Science in Sports & Exercised 929

Copyright @ 200 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited. 9 single leg press [dominate leg]) using a Body-Solid EXM3000S multistation gym. This protocol adhered to the testing guidelines recommended by the ACSM (see Table 1 for HRmax, VO2max, �� and 1RM data). Participants completed a health history and demographics questionnaire during the 10-min rest between the cardiorespiratory fitness test and the 1RM strength tests. Days 2, 3, and 4���experimental sessions. Laboratory visits 2, 3, and 4 were counterbalanced across subjects to minimize any order or learning effects. During these visits, participants completed the Sternberg task before, immediately after, and 30 min after the experimental condition, which consisted of either 30 min of aerobic exercise, resistance exercise, or seated rest. Before the start of each experimental session, participants were administered 20 practice trials. During each visit, HR and oxygen consumption were measured throughout the session using a Polar HR monitor (Model A1 Polar Electro) and a K4b2 breath-by-breath computerized indirect calorimetry system (K4b2 COSMED). The aerobic exercise session was based on the ACSM guidelines for improving aerobic capacity, with participants completing 30 min of aerobic exercise on a motor driven treadmill at an intensity of 60Q���70% of VO2max. �� The resis- tance exercise session was designed to provide an exercise stimulus similar in duration to aerobic exercise and was based upon the NCSA guidelines for improving muscular capacity (2). During the 30-min resistance exercise condition, par- ticipants completed three sets of 8���12 repetitions at 80% of their 1RM for each of the seven major muscle groups using a Body-Solid EXM3000S multistation gym. Additionally, participants were given a 60-s rest between each set and a 90-s rest between each exercise to ensure that they were able to complete at least eight repetitions during each set. If participants were unable to complete a minimum of eight repetitions, a 5% reduction in target weight on the subsequent set occurred. Lastly, the seated rest condition was designed to serve as a control condition to index the influence of repeated testing on task performance. During the seated rest condition, participants sat quietly by themselves for 30 min, were provided an assortment of popular magazines to read, and were monitored to ensure that they did not fall asleep or stand up and move around. See Table 2 for HR, oxygen consumption (VO2), �� and other condition specific information for each experimental condition. Statistical Analysis Statistical analyses were conducted for physiological measures of HR and VO2 �� using a 3 (mode: aerobic exercise, resistance exercise, seated rest) 5 (time: rest, pretest, experimental condition, posttest, 30 min posttest) repeated-measures MANOVA. Additional statistical analy- ses were conducted separately for absolute measures of RT and response accuracy using a 3 (mode: aerobic exercise, resistance exercise, seated rest) 3 (time: pretest, posttest, 30 min posttest) 3 (set size: 3 letters, 5 letters, 7 letters) repeated-measures MANOVA. Analyses of relative meas- ures of RT and response accuracy were conducted sepa- rately using a 3 (mode: aerobic exercise, resistance exercise, seated rest) 2 (time: [(posttest j pretest) / pretest] [(30 min posttest j pretest) / pretest]) 3 (set size: 3 letters, 5 letters, 7 letters) repeated-measures MANOVA. Analyses with three or more within-subjects levels used the Wilks��� lambda statistic, and post hoc comparisons were conducted using Tukey���s HSD tests. Estimates of effect size, partial eta-square (G2), were reported for significant main effects and interactions. All analyses used a signifi- cance level of P = 0.05. TABLE 2. HR, oxygen consumption (VO2), �� and other condition-specific information for each experimental condition (T1 SE). Mode Measure All All (% Max) Males Females Seated rest Average HR (bpm) 67.9 T 1.8 35.1 T 0.9 66.9 T 2.1 69.2 T 3.3 Average VO2 �� (mLIkgj1Iminj1) 4.8 T 0.3 8.9 T 0.5 5.4 T 0.3 4.0 T 0.4 Aerobic exercise Average HR (bpm) 161.6 T 2.0 83.6 T 1.0 163.5 T 2.4 159.0 T 3.2 Average VO2 �� (mLIkgj1Iminj1) 33.8 T 1.3 62.5 T 1.4 36.4 T 1.6 30.4 T 1.3 Average speed (mph) 5.3 T 0.2 ��� 5.7 T 0.2 4.8 T 0.2 Average grade (%) 1.0 T 0.0 ��� 1.0 T 0.0 1.0 T 0.0 Average RPE 11.1 T 0.3 62.2 T 1.7 11.6 T 0.3 10.5 T 0.5 Resistance exercise Average HR (bpm) 122.5 T 2.6 63.3 T 1.2 125.4 T 2.7 118.8 T 5.0 Average VO2 �� (mLIkgj1Iminj1) 12.9 T 0.8 23.9 T 1.1 14.7 T 1.0 10.5 T 0.6 Triceps press average weight (lb) 47.9 T 3.7 75.5 T 1.3 59.4 T 3.1 32.6 T 3.2 Triceps press average reps 11.6 T 0.3 ��� 11.5 T 0.4 11.8 T 0.2 Bicep curl average weight (lb) 40.3 T 3.3 70.1 T 1.5 50.6 T 2.8 26.7 T 2.6 Bicep curl average reps 11.5 T 0.2 ��� 11.3 T 0.4 11.7 T 0.2 Bench press average weight (lb) 106.5 T 10.2 74.1 T 1.2 137.2 T 9.9 65.6 T 7.5 Bench press average reps 10.6 T 0.4 ��� 10.2 T 0.5 11.2 T 0.4 Lat pull average weight (lb) 92.5 T 5.8 75.4 T 1.5 111.4 T 4.6 67.4 T 4.5 Lat pull average reps 11.7 T 0.2 ��� 11.6 T 0.2 11.7 T 0.2 Military press average weight (lb) 49.3 T 4.8 63.5 T 1.9 62.6 T 5.2 31.5 T 4.1 Military press average reps 10.1 T 0.3 ��� 9.3 T 0.5 11.2 T 0.3 Leg curl average weight (lb) 29.8 T 2.2 65.8 T 2.8 35.6 T 2.3 22.2 T 2.2 Leg curl average reps 11.8 T 0.1 ��� 11.7 T 0.2 12.0 T 0.0 Leg press average weight (lb) 116.5 T 7.3 76.1 T 1.8 127.3 T 9.3 102.2 T 10.2 Leg press average reps 11.9 T 0.1 ��� 12.0 T 0.0 11.9 T 0.1 RPE, ratings of perceived exertion during aerobic exercise average HR, mean HR during the experimental condition average VO2, �� mean oxygen consumption during the experimental condition. http://www.acsm-msse.org 930 Official Journal of the American College of Sports Medicine APPLIED SCIENCES