High-repetition Exercise Research Articles

High Load few Repetitions Exercise is better for the Cardiovascular System than low Load Many Repetitions Exercise

Blood pressure, pulse rate, and blood lactate concentration in response to resistance training are of critical significance for people, who could benefit from performing it, but to whom extreme blood pressure levels may be harmful. Traditionally high load training was held to cause an exaggerated blood pressure response but few recent studies challenged this. Since the published data is not unanimous, we examined whether longer duration with low load or high load in shorter duration would be favorable to heart rate, blood pressure, double product, and lactate levels in a group of healthy young people. Twenty-three young students performed twice, a week apart, a sequence of four sets of an exercise, once with 20 repetitions of 50% of maximal resistance of 1 Repetition Maximum and once with 10 repetitions of 75% of 1 Repetition Maximum. Heart rate was measured continuously while blood pressure and blood lactate levels were measured before exercise and after the conclusion of each set. Heart rate, blood pressure, and blood lactate levels increased significantly more following the 20, lower load repetition sets compared to the higher load 10 repetition sets. We conclude that high load low repetition exercise is less demanding on the cardiovascular system compared to lower load high repetition exercise, which should be considered in prescribing physical activity to older beginners and cardiac rehabilitation patients.

Effects Of Low-load, High-repetition Exercise And Sex On Metabolic Properties Of Skeletal Muscle

Effects Of Low-load, High-repetition Exercise And Sex On Metabolic Properties Of Skeletal Muscle

Low-Intensity Repetitive Exercise Induced Rhabdomyolysis.

Rhabdomyolysis is a rare condition caused by the proteins of damaged muscle cells entering the bloodstream and damaging the kidneys. Common symptoms of rhabdomyolysis are muscle pain and fatigue in conjunction with dark urine; kidney damage is a common symptom among these patients. We present a case of a 23-year-old woman who displayed myalgia in the upper extremities caused by low-intensity and high-repetition exercise. She was successfully diagnosed and treated for exertional rhabdomyolysis. This patient had no significant medical history that would induce this condition. We urge the emergency medical community to observe and monitor patients that complain of myalgia to ensure they are not suffering from rhabdomyolysis even in atypical cases.

Blood Ammonium and Lactate Accumulation Response to Different Training Protocols Using the Parallel Squat Exercise

Three parallel squat protocols with equal total work volume were used to determine the metabolic response of resistance exercise with different practical training protocols combining program variables in the way that they are typically prescribed in field. Sixteen men able to back squat 1.5 times their body weight participated in the study. Individualized muscular endurance (ME), strength (STR), and hypertrophy (HYP) squat workouts were developed based on a 1 repetition maximum back squat. Each protocol was performed 3-7 days apart in random order. Venous blood was obtained after 5 minutes of seated rest both before and after each workout for ammonium and lactate analysis. The ME protocol (79.8 μM [SD = 45.4], 95% confidence interval [CI]: 55.7-104.0) produced a greater change of plasma ammonium than both the HYP (45.3 μM [SD = 34.5], 95% CI: 26.9-63.6, p = 0.017) and STR (31.7 μM [SD = 52.3], 95% CI: 3.9-59.6, p = 0.006) protocols. Change of blood lactate concentration from resting levels to postexercise levels was significantly different (p = 0.005) between ME (6.1 mM [SD = 2.9], 95% CI: 4.6-7.7) and STR (3.9 mM [SD = 2.5], 95% CI: 2.6-5.2) protocols. The main finding of this study is that blood ammonium and lactate seem to accumulate in response to an increasing number of repetitions with decreasing rest time between sets. As consequence, a greater number of repetitions should be added to a resistance workout, along with a shorter rest time between sets when training for events that induce a large metabolic load. The metabolic accumulation associated with high repetition exercise may represent the need for longer recovery time between these types of workouts compared with workouts using a low number of repetitions.

Muscular Adaptations to Combinations of High- and Low-Intensity Resistance Exercises

Acute and long-term effects of resistance-training regimens with varied combinations of high- and low-intensity exercises were studied. Acute changes in the serum growth hormone (GH) concentration were initially measured after 3 types of regimens for knee extension exercise: a medium intensity (approximately 10 repetition maximum [RM]) short interset rest period (30 s) with progressively decreasing load ("hypertrophy type"); 5 sets of a high-intensity (90% of 1RM) and low-repetition exercise ("strength type"); and a single set of low-intensity and high-repetition exercise added immediately after the strength-type regimen ("combi-type"). Postexercise increases in serum GH concentration showed a significant regimen dependence: hypertrophy-type > combi-type > strength-type (p < 0.05, n = 8). Next, the long-term effects of periodized training protocols with the above regimens on muscular function were investigated. Male subjects (n = 16) were assigned to either hypertrophy/combi (HC) or hypertrophy/ strength (HS) groups and performed leg press and extension exercises twice a week for 10 weeks. During the first 6 weeks, both groups used the hypertrophy-type regimen to gain muscular size. During the subsequent 4 weeks, HC and HS groups performed combi-type and strength-type regimens, respectively. Muscular strength, endurance, and cross sectional area (CSA) were examined after 2, 6, and 10 weeks. After the initial 6 weeks, no significant difference was seen in the percentage changes of all variables between the groups. After the subsequent 4 weeks, however, 1RM of leg press, maximal isokinetic strength, and muscular endurance of leg extension showed significantly (p < 0.05) larger increases in the HC group than in the HS group. In addition, increases in CSA after this period also tended to be larger in the HC group than in the HS group (p = 0.08). The results suggest that a combination of high- and low-intensity regimens is effective for optimizing the strength adaptation of muscle in a periodized training program.

Monitoring strength training: neuromuscular and hormonal profile.

This study investigated changes induced by a single heavy resistance training session on neuromuscular and endocrine systems in trained athletes, using the same exercises for training and testing. Five different groups volunteered: track and field male sprinters (MS, N = 6), track and field female sprinters (FS, N = 6), body builders (BB, N = 6), and weight lifters performing low-repetition exercise (WLL, N = 4) and high-repetition exercise (WLH, N = 4). In training, the work performed during half and full squat exercise was monitored for mechanical power output as well as EMG analysis on leg extensor muscles of the subjects belonging to the MS, FS, and BB groups. Just before and immediately after the training session, venous blood samples were obtained for RIA determination of testosterone (T), cortisol (C), lutropin (LH), human prolactin (PRL), and follitropin (FSH) in FS and MS. In the other three groups (BB, WLH, and WLL), the hormonal profile was limited to T and human growth hormone (hGH) only. After training the power developed in full squat demonstrated a statistically significant decrease (P < 0.01) in MS and no changes in FS. The EMG activity remained constant during the training session. Consequently, the EMG/Power ratio increased in both MS and FS, although only in MS a statistical significance was noted (P < 0.05). In MS immediately after the session the levels of C, T, and LH were significantly lower (P < 0.05). No changes were found in FS. In both groups and in BB significant negative correlation was found between changes in T level and EMG/Power ratio in half squat performance. It is likely that adequate T level may compensate the effect of fatigue in FT fibers by ensuring a better neuromuscular efficiency.

Treatment of medial ligament injuries of the knee

The anatomic structures of the knee form a complex transmission system that coordinates joint position and provides stability for knee function. Ligament injury produces abnormal kinematic states that interfere with normal knee function. Because of the unequal load-sharing between the ligaments and musculotendinous units that occurs with ligament injury, complex instability patterns can develop, compromising the functional capability of the knee. Joint damage can also develop. The surgeon must restore stability to the knee by providing the appropriate tension in the anatomic structures, thus stabilizing the tibiofemoral joint and reestablishing a more normal load-sharing function of the capsular envelope and intra-articular ligaments. Isolated, limited instability, grade III medial ligament injuries can be treated nonoperatively with bracing that allows limited motion and with a high-repetition exercise program. The examiner must be aware that complex problems also can occur with grade III injuries, adversely affecting nonoperative outcome and leading to chronic instability. For more severe acute medial ligament injuries, the surgeon can accomplish acute surgical restoration of the anatomy including the mid-third capsular ligament, tibial collateral ligament, posterior oblique ligament, semimembranosus complex, and other injured knee structures (ie, anterior cruciate ligament, meniscus, vastus medialis obliquus, and semimembranosus). A well-supervised rehabilitation program follows treatment. Reconstruction of chronic medial ligament tears produces poor results.

Strength and Contractile Adaptations in the Human Triceps Surae after Isotonic Exercise

The purpose of this study was to determine whether twitch contractile properties and strength of the triceps surae could be altered by 8 weeks of low-repetition or high-repetition isotonic exercise. Subjects were randomly assigned to either the low- or high-repetition group. Before- and after-training measurements were recorded for strength and contractile properties. The contractile variables of the muscle twitch were latency, time to peak force, peak force, half-contraction time, and half-relaxation time. Strength measurements were determined utilizing a one repetition maximal (1-RM) heel-raise testing device. A two-way ANOVA with repeated measures was used to test the effect of training on each variable. Both groups showed a significant increase in 1-RM and half-relaxation time and a decrease in electrical stimulation current after the 8-week training period. It was concluded that if high-repetition exercises develop slow-twitch Type I muscle fibers and low-repetition exercises develop fast-twitch Type II fibers, training programs must be designed specifically according to the desired outcome.