Mechanical load and physiological responses of four different resistance training methods in bench press exercise.

The purpose of the study was to compare the mechanical impact and the corresponding physiological responses of 4 different and often practically applied resistance training methods (RTMs). Ten healthy male subjects (27.3 ± 3.2 years) experienced in resistance training performed 1 exhausting set of bench press exercise until exhaustion for each of the following RTMs: strength endurance (SE), fast force endurance (FFE), hypertrophy (HYP), and maximum strength (MAX). The RTMs were defined by different lifting masses and different temporal distributions of the contraction modes per repetition. Mean concentric power (P), total concentric work (W), and exercise time (EXTIME) were determined. Oxygen uptake (V[Combining Dot Above]O2) was measured during exercise and for 30 minutes postexercise. Mean V[Combining Dot Above]O2, volume of consumed O2, and excess postexercise oxygen consumption (EPOC) were calculated over 30 minutes of recovery. Maximum blood lactate concentration (LAmax) was also determined postexercise. The P was significantly higher (p < 0.01) for FFE and MAX compared with that for SE and HYP. The W was significantly higher for FFE than for all other RTMs (p < 0.01), and it was also lower for SE than for MAX (p < 0.05). EXTIME for SE was significantly higher (p < 0.01) than for all other RTMs, whereas EXTIME for MAX was significantly lower (p < 0.01) than for all other RTMs. Mean V[Combining Dot Above]O2 was significantly higher during FFE than during all other RTMs (p < 0.01). Consumed O2 was significantly higher (p < 0.05) during SE than for HYP and MAX, and it was also significantly higher for FFE and HYP compared with MAX (p < 0.05). The LAmax was significantly higher after FFE than after MAX (p < 0.05). There were no significant differences in EPOC between all RTMs. The results indicate that FFE and MAX are adequate to train muscular power despite the discrepancy in the external load. Because FFE performance achieves the highest amount in mechanical work, it may also elicit the highest total energy expenditure. The FFE challenges aerobic metabolism most and SE enables the longest EXTIME, indicating both are appropriate to enhance aerobic muscular capacities. The EPOC and LA values may indicate that energy needs covered by anaerobic metabolism are not higher during HYP and MAX compared with the RTM of lower external load.

Warming-Up Affects Performance and Lactate Distribution between Plasma and Red Blood Cells.

Warming-up (WU) is a widely used preparation for training and competition. However, little is known about the potential mechanisms of WU on performance and on the lactate distribution in the blood compartment. The purpose of the present study was to investigate whether different WU procedures affect performance and lactate distribution between plasma and red blood cells (RBCs) after maximal exercise. At three different occasions eleven subjects performed one 30 s maximal effort exercise on a cycle ergometer. Before each exercise, subjects warmed up at different intensities: 1. no WU (NWU); 2. extensive WU (EWU); 3. intensive WU (IWU). Blood samples were taken under resting conditions, after WU, and in 1 minute intervals during recovery to determine lactate concentrations [LA] in whole blood ([LA]WB), plasma ([LA]plasma) and erythrocytes ([LA]RBC). Mean power output was +58 Watt (EWU) and +60 Watt (IWU) higher compared to NWU. For each WU condition [LA]plasma and [LA]RBC differed significantly at any time point, showing greater [LA]plasma compared to [LA]RBC. The maximal effort exercise caused a rapid decrease of the [LA]RBC/[LA]plasma ratio. [LA]RBC reached the peak 3-5 minutes later than [LA]plasma depending on the WU condition. The initial increments in [LA]RBC were 10-16% lower after IWU compared to NWU and EWU. The lower increment of [LA]RBC after IWU might be due to a "higher preloading" with lactate before exercise, causing a smaller initial [LA] gradient between plasma and RBCs. It seems that the influx decreases with increasing intracellular [LA]. Another possibility one could speculate about is, that the extracellular increase in [LA] inhibits the outflux of lactate produced by the RBC itself. This inhibited export of lactate from RBCs may lead to an intracellular lactate accumulation. But the relatively fast increase in [LA]RBC and other investigations partly contradicts this possibility. Key pointsWarm-up significantly improves performance during 30 s maximal effort exercise.No differences in performance were found between extensive and intensive warm-up.Warm-up and maximal effort exercise affects the lactate distribution between plasma and RBC.Lactate influx into RBC decreases with increasing intracellular lactate concentrations.

Does combined strength training and local vibration improve isometric maximum force? A pilot study.

BACKGROUND: The aim of the study was to determine whether a combination of strength training (ST) and local vibration (LV) improved the isometric maximum force of arm flexor muscles. ST was applied to the left arm of the subjects; LV was applied to the right arm of the same subjects. The main aim was to examine the effect of LV during a dumbbell biceps curl (Scott Curl) on isometric maximum force of the opposite muscle among the same subjects. It is hypothesized, that the intervention with LV produces a greater gain in isometric force of the arm flexors than ST. METHODS: Twenty-seven collegiate students participated in the study. The training load was 70% of the individual 1 RM. Four sets with 12 repetitions were performed three times per week during four weeks. The right arm of all subjects represented the vibration trained body side (VS) and the left arm served as the traditional trained body side (TTS). RESULTS: A significant increase of isometric maximum force in both body sides (Arms) occurred. VS, however, significantly increased isometric maximum force about 43% in contrast to 22% of the TTS. CONCLUSION: The combined intervention of ST and LC improves isometric maximum force of arm flexor muscles. LEVEL OF EVIDENCE: III.

Effect of Segment-Body Vibration on Strength Parameters.

BACKGROUND: In this study, we examine the biomechanical advantage of combining localized vibrations to hamstring muscles involved in a traditional resistance training routine. METHODS: Thirty-six male and female participants with at least 2 years of experience in resistance training were recruited from the German Sport University Cologne. The participants were randomized into two training groups: vibration training group (VG) and traditional training group (TTG). Both groups underwent a 4-week training phase, where each participant worked out at 70 % of the individual 1 repeat maximum (RM-maximum load capacity of a muscle for one lift to fatigue) (4 sets with 12 repetitions each). For participants in the VG group, local vibration was additionally applied directly to hamstring muscles during exercise. A 2-week examination phase preceded the pretests. After the pretests, the subjects underwent a prescribed training for 4 weeks. At the conclusion of the training, a 2-week detraining was imposed and then the study concluded with posttests and retest. RESULTS: The measured parameters were maximum isometric force of the hamstrings and maximum range of motion and muscle tension at maximum knee angle. The study revealed a significant increase in maximum isometric force in both training groups (VG = 21 %, TTG = 14 %). However, VG groups showed an increase in their range of motion by approximately 2 %. Moreover, the muscle tension at maximum knee angle increased less in VG (approximately 35 %) compared to TG (approximately 46 %). CONCLUSIONS: We conclude that segment-body vibrations applied in resistance training can offer an effective tool to increase maximum isometric force, compared to traditional training. The cause for these findings can be attributed to the additional local vibration stimulus.

A mathematical model for lactate transport to red blood cells.

A simple mathematical model for the transport of lactate from plasma to red blood cells (RBCs) during and after exercise is proposed based on our experimental studies for the lactate concentrations in RBCs and in plasma. In addition to the influx associated with the plasma-to-RBC lactate concentration gradient, it is argued that an efflux must exist. The efflux rate is assumed to be proportional to the lactate concentration in RBCs. This simple model is justified by the comparison between the model-predicted results and observations: For all 33 cases (11 subjects and 3 different warm-up conditions), the model-predicted time courses of lactate concentrations in RBC are generally in good agreement with observations, and the model-predicted ratios between lactate concentrations in RBCs and in plasma at the peak of lactate concentration in RBCs are very close to the observed values. Two constants, the influx rate coefficient C (1) and the efflux rate coefficient C (2), are involved in the present model. They are determined by the best fit to observations. Although the exact electro-chemical mechanism for the efflux remains to be figured out in the future research, the good agreement of the present model with observations suggests that the efflux must get stronger as the lactate concentration in RBCs increases. The physiological meanings of C (1) and C (2) as well as their potential applications are discussed.

Effects of resistance training in children and adolescents: a meta-analysis.

CONTEXT: Although physiologic benefits of resistance training for children and adolescents have been well documented, the impact of age and maturity on trainability of muscle strength remains poorly understood. OBJECTIVE: To assess the effects of resistance training in different age groups and maturity levels. METHODS: We searched electronic bibliographic databases, key journals, and reference lists of reviews, book chapters, and articles. Two independent reviewers evaluated the effects of resistance training on muscle strength for prepubertal and postpubertal healthy children and adolescents (younger than 18 years) by using the results of randomized and nonrandomized controlled trials. Assessments of muscle endurance and motor performance tests (eg, vertical jump) were excluded. The influence of continuous and categorical moderator variables was assessed by meta-regression and subgroup analyses, respectively. RESULTS: The overall weighted effect size of 1.12 (95% confidence interval: 0.9-1.3) was significantly greater than 0 (P < .01). Subgroup analyses revealed "maturity" to be a significant categorical moderator variable (z = 2.50; P = .01) and positive correlation coefficients were found for the continuous variables "duration" (r = 0.28; P = .02) and "frequency" (r = 0.26; P = .03). CONCLUSIONS: The results of our analysis indicate that the ability to gain muscular strength seems to increase with age and maturational status, but there is no noticeable boost during puberty. Furthermore, study duration and the number of performed sets were found to have a positive impact on the outcome.