The Effects of Acute Resistance Exercise on Apoptotic Signaling in Untrained Males
Jeremy R. TownsendJeffrey R. StoutAdam R. JajtnerDavid D. ChurchLeopnardo P. OliveiraKyle B. BeyerMichael B. LaMonicaJoshua J. RiffeTyler W.D. MuddleRan WangKayla BakerCarleigh H. BooneAlyssa N. VaranoskeMichael J. ReddDavid H. FukudaJay R. Hoffman
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Apoptosis, or programmed cell death, is an essential physiological process regulating cellular development and is often associated with advanced stages of inflammation and disease. However, limited research has focused on skeletal muscle apoptosis as result of exercise induced muscular trauma. PURPOSE: To observe the effects of an acute lower-body resistance exercise protocol and subsequent recovery on intramuscular apoptotic signaling. METHODS: Twenty-eight untrained males (22.3 ± 3.2 y, 1.7 ± 0.1 m, 81.1 ± 15.5 kg) were assigned to either a control (CON; n=11) or exercise group (EX; n=17) and completed a lower-body resistance exercise protocol consisting of the back squat, leg press, and leg extension exercise. Skeletal muscle microbiopsies were obtained from the vastus lateralis pre-exercise (PRE), 1-hour (1HR), 5-hour (5HR), and 48-hours (48HR) post-resistance exercise. Multiplex signaling assay kits (EMD Millipore, Billerica, MA, USA) were used to quantify the total protein (Caspase-3,-8,-9) or phosphorylation status of proteins (JNK, FADD, p53, BAD, Bcl-2) specific to apoptotic signaling pathways using MAGPIX® (Luminex, Austin, TX, USA). Mann Whitney U analysis was used to determine the effects of the exercise bout on intramuscular signaling. Additionally, change scores were analyzed by magnitude based inferences to determine a mechanistic interpretation. RESULTS: Mann-Whitney U analysis revealed that resistance exercise increased JNK phosphorylation at 1H (p=0.001) and 5H (p=0.022), and FADD phosphorylation at 1H (p=0.029). No other differences observed between groups. Magnitude based inferences revealed a “Likely” increase in total Caspase 3 from PRE-5H and from PRE-48H. JNK phosphorylation was “Most Likely” increased from PRE-1H and PRE-5H and FADD was “Likely” increased from PRE-1H. BAD was “Very Likely” increased from PRE-5H and Bcl-2 was “Most Likely” increased from PRE-1H and “Likely” increased” from PRE-5H. CONCLUSION: These data show that apoptotic signaling is upregulated in response to a typical resistance exercise protocol, providing additional insight into the physiological mechanisms involved in skeletal muscle remodeling following resistance exercise.Keywords:
FADD
Leg press
Squat
1953 Strength training (ST) is beneficial in a number of health-related areas such as preservation of lean tissue, increasing bone mineral content, increasing the ability to perform activities of daily living, and enhancing quality of life. Despite the known benefits of ST, there is a lack of research on the effects of ST on the health and fitness of African American females (AAF). This study investigated the effects of eight weeks of periodized, high intensity ST on the muscle strength and endurance of sedentary AAF 44 to 68 years of age. 19 AAF were randomly assigned to a ST group (n=12, 50.7±7.0yrs, 82.8±13.1kg, 162.2±5.4cm, %bodyfat=41.7±5.4) or a control group (n=7, 52.0±8.0yrs, 90.0±4.8kg, 160.8±7.2cm, %bodyfat=44.9±3.6). Maximal strength (1RM squat press and bench press), and endurance (repetitions to failure at 70% 1RM squat press and 50% 1RM bench press) tests established baseline values. Lower and upper body ST started at 60% 1RM, progressing to 80% 1RM by week 3. Weeks 3-8, resistance was increased individually to maintain 8RM per set. Results demonstrate significant (p<0.001) muscle strength and endurance gains in the ST group (1RM: squat press = +93%, bench press = +33%; repetitions to failure: squat press = +205%, bench press = 105%). Results indicate that significant changes in muscle strength and endurance can occur from short-term, high intensity ST in older AAF. Supported by ROW grant, University of Louisville
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During the initial period of resistance training the rapid gains in muscular strength are mainly due to neuromuscular factors rather than morphological changes in the muscle tissue. It has been hypothesized that improvements in muscular strength may be elicited by simply practicing the resistance training movement and initial gains may be comparable to gains achieved through using an overload. PURPOSE: To compare changes in muscular strength in healthy older adults participating in a resistance training program using traditional resistance (TR) versus minimal resistance (MR). METHODS: 51 untrained, healthy older adults (mean±SD age: 67.5±5.9; BMI: 29.4±6.6) were recruited and randomly assigned to one of two groups: 1) TR group or 2) MR group. Training included five resistance training exercises (bench press, lat pulldown, cable upright rows, triceps pressdown, and leg curl) for three sets of ten repetitions on two days per week for four weeks. Subjects in the TR group exercised using 75% of their predicted one repetition maximum (1RM). Subjects in the MR group used a 5 ft. PVC pipe for the bench press exercise, and the lowest weight on the selectorized weight training machines for the other exercises. Following the pre-testing six follow-up tests were conducted. All five resistance training movements were tested with a 4RM to 6RM testing procedure and 1RM strength were predicted using appropriate equations. Each testing session was followed by training. Data were analyzed using a general linear mixed model and alpha level was set at p<0.05. RESULTS: Both the TR and MR groups showed significant improvement (p<0.001) in strength for all five exercises from pre- to post-test. Strength improvements in the TR group ranged from 13.1% and 36.0%, while in the MR group from 11.1% to 27.4%. Group by time interactions were not significant for the bench press (p=0.97), lat pulldown (p=0.58), cable upright row (p=0.94), triceps pressdown (p=0.31), and leg curl (p=0.29) exercises. CONCLUSIONS: Findings of this study indicate that initial improvements in muscular strength may be elicited by practicing proper exercise technique without using resistance overloads. This style of program design may provide a safe and effective method of introduction to resistance training in older adults.
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The purpose of this investigation was conducted to determine the acute effect of passive static stretching (PSS) of the lower-body musculature on lower-body strength in a 1 repetition maximum (1RM) squat exercise in young (18-24 years.) moderately trained men (n = 17). Two supervised warm-up treatments were applied before each performance testing session using a counterbalanced design on nonconsecutive days. The first treatment consisted of an active dynamic warm-up (AD) with resistance machines (i.e., leg extension/leg flexion) and free weights (i.e., barbell squat), whereas the second treatment added PSS of the lower body plus the AD treatment. One repetition maximum was determined using the maximum barbell squat following a progressive loading protocol. Subjects were also asked to subjectively evaluate their lower-body stability during 1RM testing sessions for both the AD and PSS treatments. A significant decrease in 1RM (8.36%) and lower-body stability (22.68%) was observed after the PSS treatment. Plausible explanations for this observation may be related to a more compliant muscle tendon unit and/or altered or impaired neurologic function in the active musculature. It is also possible that strength was impaired by the PSS because of joint instability. The findings of this study suggest that intensive stretching such as lower-body PSS should be avoided before training the lower body or performing the 1RM in the squat exercise in favor of an AD dynamic warm-up using resistance training equipment in the lower-body musculature.
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PURPOSE: The purpose of this investigation was conducted to determine the acute effect of passive static stretching of the lower-body musculature on lower-body strength in a one repetition maximum (1RM) squat exercise in young (18 -24 yrs.) moderately trained men (N = 17). METHODS: Two supervised warm-up treatments were applied before each performance testing session using a counterbalanced design on nonconsecutive days. The first treatment consisted of an active dynamic warm-up (AD) with resistance machines (i.e. leg extension / leg flexion) and free weights (i.e. barbell squat) while the second treatment added passive static stretching (PSS) of the lower-body before the AD treatment. 1RM was determined using the maximum barbell squat following a progressive loading protocol. Subjects were also asked to subjectively evaluate their lower-body stability / balance during 1RM testing sessions for both the AD and PSS treatments. RESULTS: Data analysis using a paired t-test of sample means revealed a significant (a = 0.05) decrease in 1RM (8.36 %) and lower-body stability / balance (22.68 %) following the PSS treatment. Plausible explanations for this observation may be related to a more compliant muscle tendon unit (MTU) and / or altered or impaired neurological function in the active musculature. It is also possible that strength and stability / balance were impaired by the PSS treatment due to joint instability. CONCLUSIONS: Intensive stretching such as lower-body PSS should be avoided prior to training the lower-body or performing the 1RM in the squat exercise in favor of an AD dynamic warm-up using resistance training equipment in the lower-body musculature.
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Background Phosphatidic acid (PA) has been reported to activate the mammalian target of rapamycin (mTOR) signaling pathway and is thought to enhance the anabolic effects of resistance training. The purpose of this pilot study was to examine if oral phosphatidic acid administration can enhance strength, muscle thickness and lean tissue accruement during an 8-week resistance training program.Methods Sixteen resistance-trained men were randomly assigned to a group that either consumed 750 mg of PA (n = 7, 23.1 ± 4.4 y; 176.7 ± 6.7 cm; 86.5 ± 21.2 kg) or a placebo (PL, n = 9, 22.5 ± 2.0 y; 179.8 ± 5.4 cm; 89.4 ± 13.6 kg) group. During each testing session subjects were assessed for strength (one repetition maximum [1-RM] bench press and squat) and body composition. Muscle thickness and pennation angle were also measured in the vastus lateralis of the subject's dominant leg.Results Subjects ingesting PA demonstrated a 12.7% increase in squat strength and a 2.6% increase in LBM, while subjects consuming PL showed a 9.3% improvement in squat strength and a 0.1% change in LBM. Although parametric analysis was unable to demonstrate significant differences, magnitude based inferences indicated that the Δ change in 1-RM squat showed a likely benefit from PA on increasing lower body strength and a very likely benefit for increasing lean body mass (LBM).Conclusions Results of this study suggest that a combination of a daily 750 mg PA ingestion, combined with a 4-day per week resistance training program for 8-weeks appears to have a likely benefit on strength improvement, and a very likely benefit on lean tissue accruement in young, resistance trained individuals.
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Endurance Training
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Strength Training
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A traditional progressive resistance exercise program consists of increasing the number of repetitions at a constant load until exceeding an established repetition range. Subsequently, the load is increased by 1.1 kg (2.5 lb) or more, and the lifter works at the new load until again exceeding the repetition range. This investigation examines the use of small incremental loads for 2 upper-body exercises (bench press and triceps press). Subjects were randomly assigned to traditional (TRAD) progressive resistance exercise (5 women, 5 men) and small increment (SI) progressive resistance exercise (5 women, 4 men) groups. Initially, both groups trained for 8 weeks using TRAD progressive resistance exercise. Subjects who achieved 7 repetitions on the final set of an exercise increased the load for the next session by 2.2 (bench press) or 1.1 kg (triceps press). Following the initial 8-week training period, the TRAD group continued for another 8 weeks following the same protocol, whereas the SI group trained for an additional 8 weeks, increasing the load by 0.22 kg (0.5 lb) when completing 7 or 8 repetitions and 0.44 kg (1 lb) when achieving 9 or more repetitions. All groups, except TRAD women, made significant increases in 1 repetition maximum (1RM) for the bench press. Both TRAD men and SI men significantly increased 1RM triceps press. Groups that did not significantly increase 1RM, in either the bench press or triceps press, demonstrated similar trends. For TRAD men and SI men, the number of repetitions to failure for the bench press at 60% 1RM decreased after training. Both regimens proved effective for increasing strength throughout 8 weeks. In conclusion, SI progressive resistance exercise appears to be as effective as TRAD progressive resistance exercise for increasing strength during 8 weeks in short-term pretrained college-aged men and women. However, preliminary data suggest that the TRAD progressive resistance exercise program might be a more effective method of increasing resistance during an extended period.
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We hypothesized that resistance training with combined eccentric and concentric actions, and concentric action only, should yield similar changes in muscular strength. Subjects in a free weight group trained three times a week for 12 wk with eccentric and concentric actions (FW, n = 16), a second group trained with concentric-only contractions using hydraulic resistance (HY; n = 12), and a control group did not train (n = 11). Training for FW and HY included five sets of supine bench press and upright squat at an intensity of 1-6 repetition maximum (RM) plus five supplementary exercises at 5-10 RM for a total of 20 sets per session for approximately 50 min. Testing at pre-, mid-, and posttraining included 1) 1 RM bench press and squat with and 2) without prestretch using free weights; 3)isokinetic peak force and power for bench press and squat at 5 degrees/s, and isotonic peak velocity and power for bench press with 20-kg load and squat with 70-kg load; 4) hydraulic peak bench press force and power, and peak knee extension torque and power at fast and slow speeds; and 5) surface anthropometry (fatfolds and girths to estimate upper arm and thigh volume and muscle area). Changes in overall fatness, muscularity, and muscle + bone cross-sectional area of the limbs did not differ between groups (P greater than 0.05). Improvements in free weight bench press and squat were similar (P greater than 0.05) in FW (approximately 24%) and HY (approximately 22%, P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
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Resistance training is known to improve muscular strength and power, though it is unclear how training volume and intensity will affect their improvement in experienced, resistance trained men. PURPOSE: Compare the effect of training volume and intensity on changes in lower body maximal strength, isometric force, and power in experienced, resistance trained men. METHODS: Following a 2-wk preparatory phase, 29 experienced, resistance trained men completed pre-testing (PRE) measures of rectus femoris (RF) and vastus lateralis (VL) activation and power output during a one repetition maximum (1RM) squat (SQ) assessment. During testing, peak (PSP) and mean (MSP) squat power was determined by a linear force transducer attached to the barbell, while muscle activation was assessed via surface electromyography at weight corresponding to 40, 60, 80, and 100% of the SQ 1RM. Peak isometric force (PIF) and rate of force development (RFD) were tested by an isometric mid-thigh pull. Participants were then matched for relative squat strength and randomly selected to complete either a low intensity, high volume (VOL, n = 14, 4x 10-12RM, 1min rest) or low volume, high intensity (INT, n = 15, 4 x 3-5RM, 3min rest) resistance training program. Participants completed post-testing following 8 wks (4 d · wk-1) of training. RESULTS: Paired-samples comparisons indicated that both groups increased 1RM SQ (VOL: 19.3 ± 9.4%, p < 0.001; INT: 16.4 ± 8.8%, p < 0.001), MSP at 100% (VOL: 14.9 ± 11.9%, p < 0.001; INT: 9.7 ± 12.3%, p = 0.030), and reduced RF activation at 100% (VOL: -23.1 ± 27.1%, p = 0.009; INT: -20.2 ± 21.8%, p = 0.005). Exclusive improvements for INT included increased VL activation during maximal SQ (19.7 ± 19.7%, p = 0.003) and PIF (7.8 ± 6.2%, p < 0.001), while VOL increased PSP at 80% 1RM (9.0 ± 15.6%, p = 0.038) and reduced RF activation at 60% (-15.6 ± 30.1%, p = 0.039). RFD did not improve in either group. Analysis of covariance, controlling for PRE, indicated that the RF activation reduction at 60% was significantly (p = 0.020) different between groups. CONCLUSIONS: In resistance trained men, greater training intensity may be more beneficial for performance at maximal loads, while greater training volume may positively influence performance at submaximal loads.
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Intensity
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Lower body
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A single bout of lower-body aerobic exercise may negatively affect a subsequent lower-body resistance exercise workout. However, less is known regarding the effects of a lower-body aerobic workout on muscle activation and performance during a subsequent upper-body resistance exercise workout. Therefore, the purpose of this study was to compare muscle activation and performance during lower- and upper-body resistance exercise workouts after a single bout of lower-body aerobic exercise on an elliptical machine. Fourteen men (mean age = 24.1 ± 2.3 years, height = 180.8 ± 6.9 cm, body mass = 91.9 ± 16.4 kg) completed 4 trials in random order. Two trials consisted of 30 minutes on the elliptical machine, using the lower body only, at 70% of age-predicted maximum heart rate before either a back squat or bench press workout, consisting of 3 sets to failure performed at 75% 1 repetition maximum. The other 2 trials consisted of only the back squat or bench press resistance workouts. To quantify muscle activation, bipolar surface electromyography electrodes were placed on the rectus femoris and vastus lateralis or pectoralis major. Acute lower-body aerobic exercise on an elliptical machine significantly reduced the number of repetitions completed for the back squat but not the bench press exercise. There was no significant difference in muscle activation between the elliptical and no elliptical conditions. However, for both exercises and conditions, muscle activation increased significantly between the first and final repetitions for the first 2 sets but not for the third set. These results suggest that to optimize the quality of a lower-body resistance-training workout, the workout should not be preceded by lower-body aerobic exercise.
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Aerobic Exercise
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Exercise physiology
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