Effects of Drop Jump Training from Different Heights and Weight Training on Vertical Jump and Maximum Strength Performance in Female Volleyball Players.

ABSTRACT: Sotiropoulos, K, Smilios, I, Barzouka, K, Christou, M, Bogdanis, G, Douda, H, and Tokmakidis, SP. Effects of drop jump training from different heights and weight training on vertical jump, maximum strength and change of direction performance in female volleyball players. J Strength Cond Res 37(2): 423-431, 2023-This study compared the effects of drop jump (DJ) training from different drop heights and weight training on vertical jump and maximum strength performance. Fifty-five female volleyball players (age: 23.8 ± 4.3 years) were randomly and equally allocated to a control group (volleyball training, CG); a volleyball and weight training group (WG); and 3 volleyball, weight, and drop jump training groups. One group performed DJ training from the optimal drop height, i.e., the height that elicited the highest ratio of jump height to contact time (OG), a second group from a drop height 25% higher than the optimal (HG), and a third group from a drop height 25% lower than the optimal (LG). Drop jump and weight training were performed 1-2 times per week, for 8 weeks for a total of 13 sessions. After training, vertical jump performance improved by 3.6-17.4% ( p < 0.05; effect size [ES]: 1.03-1.23) in the OG and the HG compared with the LG, WG, and CG ( p < 0.05; ES: 0.03-0.58). Drop jump height from drop heights 20-70 cm increased by 10.0-20.2% ( p < 0.05; ES: 0.59-1.13) for the OG and the HG, while reactive strength index increased ( p < 0.05; ES: 0.74-1.40) by 19.6-33.9% only in the HG compared with the CG. Half-squat maximum strength was increased in all experimental groups by 17.4-19% compared with the CG ( p < 0.05) with no differences ( p > 0.05) observed among them. The use of the optimal height or a moderately higher drop height by 25% for DJ training, combined with weight training, seems to be the most beneficial option to improve vertical jump and reactive strength index in female volleyball players.

Effects of Work and Recovery Duration and Their Ratio on Cardiorespiratory and Metabolic Responses During Aerobic Interval Exercise.

ABSTRACT: Myrkos, A, Smilios, I, Zafeiridis, A, Iliopoulos, S, Kokkinou, EM, Douda, H, and Tokmakidis, SP. Effects of work and recovery duration and their ratio on cardiorespiratory and metabolic responses during aerobic interval exercise. J Strength Cond Res 36(8): 2169-2175, 2022-This study examined the effect of work and recovery durations and of work-to-rest ratio (WRR) on total exercise time and oxygen consumption (V̇ o2 max), on exercise time above 80, 90, and 95% of V̇ o2 max and HRmax, and on blood lactate concentrations during aerobic interval exercise. Twelve men (22.1 ± 1 year) executed, until exhaustion, 4 interval protocols at an intensity corresponding to 100% of maximal aerobic velocity. Two protocols were performed with work bout duration of 120 seconds and recovery durations of 120 (WRR: 1:1) or 60 seconds (WRR: 2:1), and 2 protocols with work bout duration of 60 seconds and recovery durations of 60 (WRR: 1:1) or 30 seconds (WRR: 2:1). When compared at equal exercise time, total V̇ o2 and exercise time at V̇ o2 above 80, 90, and 95% of V̇ o2 max were longer ( p < 0.05) in 120:120, 120:60 and 60:30 vs. the 60:60 protocol. When analyzed for total exercise time (until exhaustion), total V̇ o2 was higher ( p < 0.01) in the 60:60 compared with all other protocols, and in the 120:120 compared with 120:60. Exercise time >95% of V̇ o2 max and HRmax was higher ( p < 0.05) in the 120:120 vs. the 60:60 protocol; there were no differences among protocols for exercise time >90% of V̇ o2 max and HRmax. Blood lactate was lower ( p < 0.05) in the 60:60 compared with all other protocols and in the 60:30 vs. the 120:60. In conclusion, when interval exercise protocols are executed at similar effort (until exhaustion), work and recovery durations do not, in general, affect exercise time at high oxygen consumption and HR rates. However, as work duration decreases, a higher work-to-recovery ratio (e.g., 2:1) should be used to achieve and maintain high (>95% of maximum) cardiorespiratory stimulus. Longer work bouts and higher work-to-recovery ratio seem to activate anaerobic glycolysis to a greater extent, as suggested by greater blood lactate concentrations.

The Effects of Recovery Duration During High-Intensity Interval Exercise on Time Spent at High Rates of Oxygen Consumption, Oxygen Kinetics, and Blood Lactate.

Smilios, I, Myrkos, A, Zafeiridis, A, Toubekis, A, Spassis, A, and Tokmakidis, SP. The effects of recovery duration during high-intensity interval exercise on time spent at high rates of oxygen consumption, oxygen kinetics, and blood lactate. J Strength Cond Res 32(8): 2183-2189, 2018-The recovery duration and the work-to-recovery ratio are important aspects to consider when designing a high-intensity aerobic interval exercise (HIIE). This study examined the effects of recovery duration on total exercise time performed above 80, 90, and 95% of maximum oxygen consumption (V[Combining Dot Above]O2max) and heart rate (HRmax) during a single-bout HIIE. We also evaluated the effects on V[Combining Dot Above]O2 and HR kinetics, blood lactate concentration, and rating of perceived exertion (RPE). Eleven moderately trained men (22.1 ± 1 year) executed, on 3 separate sessions, 4 × 4-minute runs at 90% of maximal aerobic velocity (MAV) with 2, 3, and 4 minutes of active recovery. Recovery duration did not affect the percentage of V[Combining Dot Above]O2max attained and the total exercise time above 80, 90, and 95% of V[Combining Dot Above]O2max. Exercise time above 80 and 90% of HRmax was longer with 2 and 3 minutes (p ≤ 0.05) as compared with the 4-minute recovery. Oxygen uptake and HR amplitude were lower, mean response time slower (p ≤ 0.05), and blood lactate and RPE higher with 2 minutes compared with 4-minute recovery (p ≤ 0.05). In conclusion, aerobic metabolism attains its upper functional limits with either 2, or 3 or 4 minutes of recovery during the 4 × 4-minute HIIE; thus, all rest durations could be used for the enhancement of aerobic capacity in sports, fitness, and clinical settings. The short (2 minutes) compared with longer (4 minutes) recovery, however, evokes greater cardiovascular and metabolic stress and activates to a greater extent anaerobic glycolysis and hence, could be used by athletes to induce greater overall physiological challenge.

Contrast Loading Increases Upper Body Power Output in Junior Volleyball Athletes.

PURPOSE: This study examined the acute effects of contrast loading on mechanical power output during bench-press throws in junior volleyball players. METHOD: Eleven males (age: 16.5 ± 0.5 years) performed a contrast loading and a control protocol. The contrast protocol included the execution of 3 bench-throws with a 30% load of 1RM, after 3 min a conditioning set of 5 bench-throws with a 60% load of 1RM and after 3 and 5 min two more sets of 3 bench-throws with a 30% load of 1RM. The control protocol included the execution of 3 sets of 3 bench-throws with a 30% load of 1RM at the same time points as in the contrast protocol without the execution of the conditioning set. RESULTS: Mechanical power with a 30% load was higher (p < .05) 3 and 5 min following the conditioning set at the contrast protocol compared with the control protocol (8.7 ± 7.5 and 10.4 ± 3.4%, respectively). High correlations (p < .05) were obtained between participant's relative maximal strength (r = .87) and power (r = .82) and the increases in power output. CONCLUSION: Contrast loading increases upper body power output produced with a light load by junior athletes. The potential for increased upper body performance is more evident in stronger or more powerful individuals.

Aerobic, resistance and combined training and detraining on body composition, muscle strength, lipid profile and inflammation in coronary artery disease patients.

Fifty-six elderly individuals diagnosed with coronary artery disease participated in the study and were divided into four groups: an aerobic exercise group, a resistance exercise group, a combined (aerobic + resistance) exercise group and a control group. The three exercise groups participated in 8 months of exercise training. Before, at 4 and at 8 months of the training period as well as at 1, 2 and 3 months after training cessation, muscle strength was measured and blood samples were collected. The resistance exercise caused significant increases mainly in muscle strength whereas aerobic exercise caused favourable effects mostly on lipid and apolipoprotein profiles. On the other hand, combined exercise caused significant favourable effects on both physiological (i.e. muscle strength) and biochemical (i.e. lipid and apolipoprotein profile and inflammation status) parameters, while the return to baseline values during the detraining period was slower compared to the other exercise modalities.

Community-Based Training-Detraining Intervention in Older Women: A Five-Year Follow-Up Study.

This five-year follow-up nonrandomized controlled study evaluated community-based training and detraining on body composition and functional ability in older women. Forty-two volunteers (64.3 ± 5.1 years) were divided into four groups: aerobic training, strength training, combined aerobic and strength, and control. Body composition and physical fitness were measured at baseline, after nine months of training and after three months of detraining every year. After five years of training, body fat decreased, and fat free mass, strength, and chair test performance increased (p < .05) in all training groups. Training-induced favorable adaptations were reversed during detraining but, eventually, training groups presented better values than the control group even after detraining. Thus, nine months of annual training, during a five-year period, induced favorable adaptations on body composition, muscular strength, and functional ability in older women. Three months of detraining, however, changed the favorable adaptations and underlined the need for uninterrupted exercise throughout life.

Physical Improvement and Biological Maturity of Young Athletes (11-12 Years) with Systematic Training.

AIM: The aim of this study was to investigate the influence of systematic training in physical growth and biological maturity in prepubertal males and estimate how this affects the physical growth and skeletal maturity. MATERIALS AND METHODS: 177 primary school students of the fifth and sixth grade, from schools in Alexandroupolis, participated voluntarily in our study. Questionnaires were used in order to measure physical activity levels. The subjects were subdivided into two groups; control group (prepubertal, whose physical activity was the physical education of their school and which had never participated in systematic training, n = 95) and experimental group (prepubertal, whose weekly physical activity included physical education in their schools and additionally 3-4 training units organized training in various sports clubs in the city, n = 82). The following parameters were recorded: biological age measured by determination of skeletal age; bone density measured by ultrasound methods; anthropometric and morphological features such as height, body composition, selected diameters, circumferences and skinfolds; motor ability features. RESULTS: The experimental group exhibited older biological age (p = 0.033), higher bone density (p < 0.001), lower BMI and body fat (p < 0.001), better anthropometric features and higher performance throughout all motor ability tests (p < 0.05), compared to the control group. CONCLUSION: The present study demonstrates that systematic physical activity has a positive effect on both the physical and biological maturity of pre-pubertal children. This effect is mainly expressed in bone strengthening as a result of the increased bone density and in improvement of the kinetic skills of pupils who participated in organized extracurricular sport-activities.

Acute pro- and anti-inflammatory responses to resistance exercise in patients with coronary artery disease: a pilot study.

Little is known about the inflammatory effects of resistance exercise in healthy and even less in diseased individuals such as cardiac patients. The purpose of this study was to examine the acute pro- and anti-inflammatory responses during resistance exercise (RE) in patients with coronary artery disease. Eight low risk patients completed two acute RE protocols at low (50% of 1 RM; 2x18 rps) and moderate intensity (75% of 1 RM; 3x8 rps) in random order. Both protocols included six exercises and had the same total load volume. Blood samples were obtained before, immediately after and 60 minutes after each protocol for the determination of lactate, TNFα, INF-γ, IL-6, IL-10, TGF-ß1, and hsCRP concentrations. IL-6 and IL-10 levels increased (p < 0.05) immediately after both RE protocols with no differences between protocols. INF-γ was significantly lower (p < 0.05) 60 min after the low intensity protocol, whereas TGF-ß1 increased (p < 0.05) immediately after the low intensity protocol. There were no differences in TNF-& and hs-CRP after both RE protocols or between protocols. The above data indicate that acute resistance exercise performed at low to moderate intensity in low risk, trained CAD patients is safe and does not exacerbate the inflammation associated with their disease. Key pointsAcute resistance exercise is safe without exacerbating inflammation in patients with CAD.Both exercise intensities (50 and 75% of 1 RM) elicit desirable pro-and anti-inflammatory responses.With both exercise intensities (50 and 75% of 1 RM) acceptable clinical hemodynamic alterations were observed.

Metabolic responses at various intensities relative to critical swimming velocity.

To avoid any improper training load, the speed of endurance training needs to be regularly adjusted. Both the lactate threshold (LT) velocity and the velocity corresponding to the maximum lactate steady state (MLSS) are valid and reliable indices of swimming aerobic endurance and commonly used for evaluation and training pace adjustment. Alternatively, critical velocity (CV), defined as the velocity that can be maintained without exhaustion and assessed from swimming performance of various distances, is a valid, reliable, and practical index of swimming endurance, although the selection of the proper distances is a determinant factor. Critical velocity may be 3-6 and 8-11% faster compared with MLSS and LT, respectively. Interval swimming at CV will probably show steady-lactate concentration when the CV has been calculated by distances of 3- to 15-minute duration, and this is more evident in adult swimmers, whereas increasing or decreasing lactate concentration may appear in young and children swimmers. Therefore, appropriate corrections should be made to use CV for training pace adjustment. Findings in young and national level adult swimmers suggest that repetitions of distances of 100-400 m, and velocities corresponding to a CV range of 98-102% may be used for pacing aerobic training, training at the MLSS, and possibly training for improvement of VO2max. Calculation of CV from distances of 200-400, 50-100-200-400, or 100-800 m is an easy and practical method to assess aerobic endurance. This review intends to study the physiological responses and the feasibility of using CV for aerobic endurance evaluation and training pace adjustment, to help coaches to prescribe training sets for different age-group swimmers.

Maximum power training load determination and its effects on load-power relationship, maximum strength, and vertical jump performance.

This study examines the changes in maximum strength, vertical jump performance, and the load-velocity and load-power relationship after a resistance training period using a heavy load and an individual load that maximizes mechanical power output with and without including body mass in power calculations. Forty-three moderately trained men (age: 22.7 ± 2.5 years) were separated into 4 groups, 2 groups of maximum power, 1 where body mass was not included in the calculations of the load that maximizes mechanical power (Pmax - bw, n = 11) and another where body mass was included in the calculations (Pmax + bw, n = 9), a high load group (HL-90%, n = 12), and a control group (C, n = 11). The subjects performed 4-6 sets of jump squat and the repeated-jump exercises for 6 weeks. For the jump squat, the HL-90% group performed 3 repetitions at each set with a load of 90% of 1 repetition maximum (1RM), the Pmax - bw group 5 repetitions with loads 48-58% of 1RM and the Pmax + bw 8 repetitions with loads 20-37% of 1RM. For the repeated jump, all the groups performed 6 repetitions at each set. All training groups improved (p < 0.05) maximum strength in the semisquat exercise (HL-90%: 15.2 ± 7.1, Pmax - bw: 6.6 ± 4.7, Pmax + bw: 6.9 ± 7.1, and C: 0 ± 4.3%) and the HL-90% group presented higher values (p < 0.05) than the other groups did. All training groups improved similarly (p < 0.05) squat (HL-90%: 11.7 ± 7.9, Pmax - bw: 14.5 ± 11.8, Pmax + bw: 11.3 ± 7.9, and C: -2.2 ± 5.5%) and countermovement jump height (HL-90%: 8.6 ± 7.9, Pmax - bw: 10.9 ± 9.4, Pmax + bw: 8.8 ± 4.3, and C: 0.4 ± 6%). The HL-90% and the Pmax - bw group increased (p < 0.05) power output at loads of 20, 35, 50, 65, and 80% of 1RM and the Pmax + bw group at loads of 20 and 35% of 1RM. The inclusion or not of body mass to determine the load that maximizes mechanical power output affects the long-term adaptations differently in the load-power relationship. Thus, training load selection will depend on the required adaptations. However, the use of heavy loads causes greater overall neuromuscular adaptations in moderately trained individuals.

Physiological responses and stroke-parameter changes during interval swimming in different age-group female swimmers.

The purpose of the study was to examine the physiological responses, the stroke-parameter changes, and the ability to sustain a velocity corresponding to critical velocity (CV) during interval swimming on female swimmers of different age groups. Eight children (C; age: 10.4 ± 0.6 years), 11 young (Y; age: 13.1 ± 0.4 years), and 7 adults (A; age: 19.9 ± 4.6 years) swam all-out efforts of 50, 100, 200, 400 m for CV and critical stroke rate (CSR) calculation. Subsequently, the swimmers performed an interval training set of 5 × 300-m (C) and 5 × 400-m repetitions (Y and A) at a velocity corresponding to CV. The CV was higher in the Y and A compared with the C group (C: 0.962 ± 0.05, Y: 1.168 ± 0.09, A: 1.217 ± 0.05 m·s(-1), p < 0.05). The velocity of 5 × 300 and 5 × 400 m was not different compared with CV (C: 100 ± 2%, Y: 98 ± 3%, A: 98 ± 3% of CV, p > 0.05). The blood lactate concentration was similar between groups and was maintained steady within each group (C: 4.5 ± 1.4, Y: 4.9 ± 1.4, A: 3.9 ± 1.3 mmol·L(-1), p > 0.05). Heart rate was higher in the C and Y compared with the A group during the last 100 m of each repetition (p < 0.05). Stroke rate remained unchanged during the repetitions and was similar between groups and no different to the CSR (p > 0.05). Stroke length of the fifth repetition was 4.5 ± 4.0% shorter compared with the second repetition in the Y and 5.3 ± 2.0% shorter compared with the first repetition in the A group (p < 0.05). During the 28- to 31-minute duration intermittent swimming, children and young and adult female swimmers were able to sustain CV with a steady and similar blood lactate concentration. Decreased stroke length may indicate an earlier fatigue in young and adult swimmers.

Endothelial progenitor cell mobilization based on exercise volume in patients with cardiovascular disease and healthy individuals: a systematic review and meta-analysis.

Endothelial progenitor cells (EPCs) play a vital role in protecting endothelial dysfunction and cardiovascular disease (CVD). Physical exercise stimulates the mobilization of EPCs, and along with vascular endothelial growth factor (VEGF), promotes EPC differentiation, and contributes to vasculogenesis. The present meta-analysis examines the exercise-induced EPC mobilization and has an impact on VEGF in patients with CVD and healthy individuals. Database research was conducted (PubMed, EMBASE, Cochrane Library of Controlled Trials) by using an appropriate algorithm to indicate the exercise-induced EPC mobilization studies. Eligibility criteria included EPC measurements following exercise in patients with CVD and healthy individuals. A continuous random effect model meta-analysis (PROSPERO-CRD42019128122) was used to calculate mean differences in EPCs (between baseline and post-exercise values or between an experimental and control group). A total of 1460 participants (36 studies) were identified. Data are presented as standard mean difference (Std.MD) and 95% confidence interval (95% CI). Aerobic training stimulates the mobilization of EPCs and increases VEGF in patients with CVD (EPCs: Std.MD: 1.23, 95% CI: 0.70-1.76; VEGF: Std.MD: 0.76, 95% CI:0.16-1.35) and healthy individuals (EPCs: Std.MD: 1.11, 95% CI:0.53-1.69; VEGF: Std.MD: 0.75, 95% CI: 0.01-1.48). Acute aerobic exercise (Std.MD: 1.40, 95% CI: 1.00-1.80) and resistance exercise (Std.MD: 0.46, 95%CI: 0.10-0.82) enhance EPC numbers in healthy individuals. Combined aerobic and resistance training increases EPC mobilization (Std.MD:1.84, 95% CI: 1.03-2.64) in patients with CVD. Adequate exercise volume (>60%VO2max >30 min; P = 0.00001) yields desirable results. Our meta-analysis supports the findings of the literature. Exercise volume is required to obtain clinically significant results. Continuous exercise training of high-to-moderate intensity with adequate duration as well as combined training with aerobic and resistance exercise stimulates EPC mobilization and increases VEGF in patients with CVD and healthy individuals.

Seasonal aerobic performance variations in elite soccer players.

The purpose of this study was to examine the seasonal changes in body composition and aerobic performance in elite soccer players. Twelve elite professional soccer players (aged 25 6 5 years, weight 75.7 6 5.3 kg, height 1.79 6 0.06 m) were measured for body fat (%), maximum oxygen consumption (VO2max), running velocity at VO2max (VO2max), running velocity at a fixed blood lactate concentration of 4 mmol · L21 (v-4 mM) at the start of the preseason period, at the beginning of the competitive period, and at midseason. VO2max, v-4 mM, and vVO2max increased significantly (p , 0.05) by 4.5, 10.5, and 7.8,respectively, after the preseason period. Thereafter, the aerobic performance parameters remained relatively constant, with no significant changes throughout the competitive period. The results of this study suggest that moderate improvements were observed in VO2max, and the %VO2max at 4 v-4 mM, whereas higher improvements were observed in VO2max and v-4 mmol · L21 after the preseason training period. On the other hand, during the competitive period, aerobic performance remained unchanged.In addition, this study suggests that heart rate, lactate, vVO2, and VO2max are useful and practical predictors that help monitor aerobic performance changes during a soccer season.

Training-induced changes on blood lactate profile and critical velocity in young swimmers.

This study examines the efficacy of critical swimming velocity (CV) for training prescription and monitoring the changes induced on aerobic endurance after a period of increased training volume in young swimmers. An experimental group (E: n = 7; age: 13.3 ± 1.3 years), which participated in competitive training was tested at the beginning (W0), the sixth week (W6), and 14th week (W14) to compare the changes of aerobic endurance indexes (CV; lactate threshold [LT]; velocity corresponding to blood lactate concentration of 4 mmol · L: V4). A control group (C: n = 7; age: 14.1 ± 1.6 years), which refrained from competitive training, was used to observe maturation effects and was tested for CV changes between W0 and W14. The average weekly training volume was increased after the sixth week in the E group and was unchanged for the C group. The CV was not different between or within groups at W0 and W14 (p > 0.05). The LT of the E group was no different compared to V4 and CV at W0 and W6 (p > 0.05) but was higher than CV at W14 (p < 0.05). The LT increased (6.5 ± 5.3%, p < 0.05), but V4 and CV were unchanged after W6 (3.6 ± 1.9%; 2.1 ± 1.2%, p > 0.05). LT, V4, and CV were unchanged despite the increased training volume from W6 to W14 (LT: 1.2 ± 4.3%, V4: 0.8 ± 1.5%, CV: 0.3 ± 0.8%; p > 0.05). These findings suggest that CV pace may be effectively used for the improvement of aerobic endurance in young swimmers. The aerobic endurance indexes used for the assessment of swimmers' progression showed different rates of change as a response to the same training stimulus and cannot be used interchangeably for training planning.

Repeated sprint swimming performance after low- or high-intensity active and passive recoveries.

The purpose of this study was to examine the effects on sprint swimming performance after low- and high-intensity active recovery (AR) as compared to passive recovery. Ten male competitive swimmers (age: 17.9 ± 2.3 years; body mass: 73.2 ± 4.0 kg; height: 1.81 ± 0.04 m, 100-m best time: 54.90 ± 1.96 seconds) performed 8 × 25-m sprints with 120-second rest intervals followed by a 50-m sprint 6 minutes later. During the 120-second and the 6-minute interval periods swimmers rested passively (PAS) or swam at an intensity of 40% (ACT40; 36 ± 8% of the V(O2)max) and 60% (ACT60; 59 ± 7% of the V(O2)max) of their individual 100-m velocity. Performance time of the 8 × 25-m after ACT60 was slower compared with PAS and ACT40, but no difference was observed between ACT40 and PAS conditions (PAS: 12.15 ± 0.48, ACT40: 12.23 ± 0.54, ACT60: 12.35 ± 0.57 seconds, p < 0.05). Performance time of the 50-m sprint was no different between conditions (PAS: 26.45 ± 0.91; ACT40: 26.30 ± 1.18; ACT60: 26.21 ± 1.19 seconds; p > 0.05). Blood lactate concentration was not different between PAS, ACT40, and ACT60 after the 8 × 25-m and the 50-m sprints (p > 0.05). Passive recovery, or low intensity of AR (40% of the 100-m velocity), is advised to maintain repeated 25-m sprint swimming performance when a 2-minute interval period is provided. Active recovery at an intensity corresponding to 60% of the 100-m velocity decreases performance during the 25-m repeated sprints without affecting the performance time on a subsequent longer duration sprint (i.e., 50 m).

Power output and electromyographic activity during and after a moderate load muscular endurance session.

The purpose of this study was to examine (a) the mechanical power and the electromyographic (EMG) activity during a moderate load muscular endurance session and (b) the maximal mechanical power output and EMG activity using a light load and a heavy load afterward. Sixteen men (age: 20.7 +/- 1.1 years) performed 4 sets of 20 repetitions with an initial load of 50% of 1 repetition maximum (1RM), and 2 minutes of rest, in the squat exercise. Furthermore, the subjects performed 4 repetitions with loads of 40 and 80% of 1RM before, immediately after, and 30 minutes after the end of the session. Average power and EMG activity from vastus medialis (VM), vastus lateralis (VL), and rectus femoris (RF) were recorded during the concentric phase of the lift. Average power did not change during the first 2 sets, while it decreased (p < 0.05) during the third and the fourth set. Average quadriceps (AQ), VM, VL, and RF activity increased (p < 0.05) until the 11th repetition, approximately, during each set while it increased gradually from set to set. Maximal power and AQ, VM, and VL activity with the loads of 40 and 80% of 1RM were decreased (p < 0.05) after the session. Blood lactate reached 10.2 +/- 2.5 and 13.1 +/- 4.1 mmolxL after the second and the fourth set, respectively. It appears that during a muscular endurance session with submaximal power output, mechanical performance may gradually decrease, probably due to metabolic fatigue, while muscle electrical activity may increase. Following this type of a session, maximal power output and muscle activation with a light and especially with a heavy load are reduced.

Effects of warm-up on vertical jump performance and muscle electrical activity using half-squats at low and moderate intensity.

The purpose of this study was to determine the effects of a specific warm-up using half-squats at low and moderate intensity on vertical jump performance and electromyographic activity of the thigh muscles. The subjects were 26 men who were divided into a low intensity group (LIG; n = 13) and a moderate intensity group (MIG; n = 13). The LIG performed a specific warm-up protocol that included the explosive execution of half-squats with loads 25 and 35% of the one repetition maximum (1RM) and the MIG with loads 45 and 65% of the 1RM. The two groups performed a countermovement jump (CMJ) before and three minutes after the specific warm-up protocols. During the concentric phase of the CMJ a linear encoder connected to an A/D converter interfaced to a PC with a software for data acquisition and analysis allowed the calculation of average mechanical power. The electromyographic (EMG) activity of the vastus lateralis (VL), vastus medialis (VM) and rectus femoris (RF) were recorded during the concentric phase of the jumps. The average quadriceps (Qc) activity (mean value of the VL, VM and RF) was also calculated. A two way ANOVA (protocols X time) with repeated measures on the second factor was used to analyze the data. Following the specific warm-up procedure both groups improved (p ≤ 0.05) CMJ performance and mechanical power by 3.5% and 6.3%, respectively, with no differences observed between the two groups. EMG activity of the Qc and VL increased (p ≤ 0.05) for both groups by 5.9% and 8.5%, respectively. It is concluded that the use of a specific warm-up that includes half-squats, performed explosively with low to moderate intensity, improves CMJ performance. This may be due to increased muscle activation as evaluated by the surface EMG. Key pointsThe inclusion of two sets of explosively performed half squats with low to moderate loads in the warm up procedure elicited an acute performance en-hancement.The performance was enhanced regardless of the load used in the warm-up.The performance enhancement is accompanied by a greater electromyographic activity of the knee extensors muscles.

Lipoprotein profile, glycemic control and physical fitness after strength and aerobic training in post-menopausal women with type 2 diabetes.

We studied the effects on blood lipids and physical fitness after a training program that combined strength and aerobic exercise in postmenopausal women with type 2 diabetes. Ten patients (55.0 +/- 5.2 years) followed four exercise sessions per week, two strength and two aerobic, and ten (59.4 +/- 3.2 years) served as a control group. Lipid profile, glycated hemoglobin (HbA(1c)), HOMA2 index, exercise stress and muscular testing were assessed at the beginning and after 16 weeks of training program. Exercise training increased significantly HDL-C (17.2%; P < 0.001) and decreased triglycerides (18.9%), HbA(1c) (15.0%), fasting plasma glucose (5.4%), insulin resistance (HOMA2 25.2%) and resting blood pressure (P < 0.01). After 16 weeks of training, exercise time (17.8%) and muscular strength increased significantly (P < 0.001). The results indicated that a combined strength and aerobic training program could induce positive adaptations on lipid profile, glycemic control, insulin resistance, cardiovascular function, and physical fitness in post-menopausal women with type 2 diabetes.

Training, detraining and retraining effects after a water-based exercise program in patients with coronary artery disease.

OBJECTIVE: The aim of this study was to investigate the adaptations of a water-based training program as well as the detraining and retraining effects on physiological parameters in patients with coronary artery disease (CAD). METHODS: Twenty-one patients were separated in an exercise group (n = 11) and a control group (n = 10). The exercise group followed three periods: training, detraining and retraining. Each period lasted 4 months. During the training and the retraining periods, the patients performed four sessions of water exercise (not swimming) per week. RESULTS: The water-based program was well-accepted and no adverse effects were observed. The exercise group improved (p < 0.05) their stress-test time (+11.8%), VO(2 peak) (+8.4%) and total body strength (+12.2%) after the training period; detraining tended to reverse these positive adaptations. Resumption of training increased the beneficial effects obtained after the initial training period (exercise stress: +4.5%; VO(2 peak): +6.6%; total strength: +7.0%). The patients in the control group did not show any significant alterations throughout the study. CONCLUSION: Water-based exercise is safe and induces positive physiological and muscular adaptations in low-risk patients with CAD. These could be reversed, however, after the cessation of exercise. This is why uninterrupted exercise throughout life is a must.

Active recovery intervals restore initial performance after repeated sprints in swimming.

The purpose of this study was to examine the effects of active recovery (AR) and passive recovery (PR) using short (2-min) and long (4-min) intervals on swimming performance. Twelve male competitive swimmers completed a progressively increasing speed test of 7 × 200-m swimming repetitions to locate the speed before the onset of curvilinear increase in blood lactate concentration (LT1). Subsequently, performance time of 6 × 50-m sprints was recorded during four different conditions: (i) 2-min PR (PR-2), (ii) 4-min PR (PR-4), (iii) 2-min AR (AR-2) and (iv) 4-min AR (AR-4) intervals. Blood lactate concentration was measured before the first and after the last 50-m repetition. AR was applied at an intensity corresponding to LT1. Performance as indicated by the time needed to complete 6 × 50-m sprints was impaired after AR-4 compared to PR-4 (AR-4: 28.65 ± 1.04, PR-4: 28.17 ± 0.72 s; mean% difference: MD% ±s; ±90% confidence limits: 90%CL, 1.71 ± 3.01%; ±1.43%, p = .01) but was not different between AR-2 compared to PR-2 conditions (AR-2: 28.68 ± 0.85, PR-2: 28.69 ± 0.82 s; MD%: 0.03 ± 1.61%; 90%CL ± 0.77%, p = .99). Performance in sprint-6 was improved after AR compared to PR independent of interval duration (AR: 28.55 ± 0.81, PR: 29.01 ± 1.03 s; MD%: 1.52 ± 2.61%; 90%CL ± 1.2%; p = .03). Blood lactate concentration was lower after AR-4 compared to PR-4 but did not differ between AR-2 and PR-2 conditions. In conclusion, AR impaired performance after a 4-min but not after a 2-min interval. A better performance during sprint-6 after AR could be attributed to a faster metabolic recovery or anticipatory regulatory mechanisms towards the end of the series especially when adequate 4-min active recovery interval is applied.