Physiological effects of tapering in highly trained athletes.

This study examined some of the physiological and performance effects of three different tapers in highly trained athletes. After 8 wk of training, nine male middle-distance runners were randomly assigned to one of three different 7-day tapers: a high-intensity low-volume taper (HIT), a low-intensity moderate-volume taper (LIT), or a rest-only taper (ROT). After the first taper, subjects resumed training for 4 wk and performed a second taper and then resumed training for 4 wk and completed the remaining taper, so that each subject underwent all three tapers. Performance was measured before and after each taper by a treadmill run to fatigue at a velocity equivalent each subject's best 1,500-m time. Voluntary isometric strength and evoked contractile properties of the quadriceps were measured before and after each taper, as were muscle glycogen concentration and citrate synthase activity (from needle biopsies) and total blood and red cell volume by 125I and 51Cr tagging. Maximal O2 consumption was unaffected by all three tapers, but running time to fatigue increased significantly after HIT (+22%). It was unaffected by LIT (+6%) and ROT (-3%) procedure. Citrate synthase activity increased significantly with HIT and decreased significantly with ROT. Muscle glycogen concentration increased significantly after ROT and HIT, and strength increased after all three tapers. Total blood volume increased significantly after HIT and decreased after ROT.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of high-intensity swimming training on GLUT-4 and glucose transport activity in rat skeletal muscle.

This study was performed to assess the effects of short-term, extremely high-intensity intermittent exercise training on the GLUT-4 content of rat skeletal muscle. Three- to four-week-old male Sprague-Dawley rats with an initial body weight ranging from 45 to 55 g were used for this study. These rats were randomly assigned to an 8-day period of high-intensity intermittent exercise training (HIT), relatively high-intensity intermittent prolonged exercise training (RHT), or low-intensity prolonged exercise training (LIT). Age-matched sedentary rats were used as a control. In the HIT group, the rats repeated fourteen 20-s swimming bouts with a weight equivalent to 14, 15, and 16% of body weight for the first 2, the next 4, and the last 2 days, respectively. Between exercise bouts, a 10-s pause was allowed. RHT consisted of five 17-min swimming bouts with a 3-min rest between bouts. During the first bout, the rat swam without weight, whereas during the following four bouts, the rat was attached to a weight equivalent to 4 and 5% of its body weight for the first 5 days and the following 3 days, respectively. Rats in the LIT group swam 6 h/day for 8 days in two 3-h bouts separated by 45 min of rest. In the first experiment, the HIT, LIT, and control rats were compared. GLUT-4 content in the epitrochlearis muscle in the HIT and LIT groups after training was significantly higher than that in the control rats by 83 and 91%, respectively. Furthermore, glucose transport activity, stimulated maximally by both insulin (2 mU/ml) (HIT: 48%, LIT: 75%) and contractions (25 10-s tetani) (HIT: 55%, LIT: 69%), was higher in the training groups than in the control rats. However, no significant differences in GLUT-4 content or in maximal glucose transport activity in response to both insulin and contractions were observed between the two training groups. The second experiment demonstrated that GLUT-4 content after HIT did not differ from that after RHT (66% higher in trained rats than in control). In conclusion, the present investigation demonstrated that 8 days of HIT lasting only 280 s elevated both GLUT-4 content and maximal glucose transport activity in rat skeletal muscle to a level similar to that attained after LIT, which has been considered a tool to increase GLUT-4 content maximally.     

IMPACT OF THREE DIFFERENT MATCHING METHODS ON PATIENT SET-UP ERROR IN X-RAY VOLUMETRIC IMAGING FOR HEAD AND NECK CANCER

Impact of three different matching methods for delivery of Volumetric Modulated Arc Therapy (VMAT) in Cone-beam computed tomography (CBCT) on patient set-up error. As per institutional imaging protocol, 300 CBCT scans of 20 VMAT head and neck cancer patients treated with 60 Gy/30 fractions were chosen for the present study. Approved CT images of the plan were registered as a reference with the CBCT images on board. Grey-scale matching (GM), manual matching (MM), and bone matching (BM) between on-board CBCT and reference CT images were used to assess patient translation errors. Patient positioning verification was evaluated using the Clip-box registration in all three matching methods. Using the GM approach as a reference point, two additional matchings were rendered in offline mode using BM and MM. For analysis, random error (σ), systematic error (∑), maximum error (E) mean set-up error (M), mean displacement vector (R), matching time (Mt), and multiple comparisons using Post hoc Tukey's HSD test were performed. In MM, less random and systematic errors were found than in GM and BM with an insignificant difference (p > 0.05) Compared to BM and GM, the maximum error, mean set-up error, and displacement vector were marginally less in MM (p > 0.05). In MM, an increased Mt relative to BM and GM was observed (p > 0.05). Furthermore, an insignificant difference in set-up error was revealed in a multiple comparison test (p > 0.05). Any of the three matching methods can be used during CBCT to check patient translation errors for the delivery of the VMAT head and neck patients.     

Effects of taper on swimming force and swimmer performance after an experimental ten-week training program

The purpose of this research was to examine how an 11-day taper after an 8.5-week experimental training cycle affected lactate levels during maximal exercise, mean force, and performance in training swimmers, independent of shaving, psychological changes, and postcompetition effects. Fourteen competition swimmers with shaved legs and torsos were recruited from the S?o Paulo Aquatic Federation. The training cycle consisted of a basic training period (endurance and quality phases) of 8.5 weeks, with 5,800 m.d(-1) mean training volume and 6 d.wk(-1) frequency; and a taper period (TP) of 1.5 weeks' duration that incorporated a 48% reduction in weekly volume without altering intensity. Attained swimming force (SF) and maximal performance over 200-m maximal swim (Pmax) before and after taper were measured. After taper, SF and Pmax improved 3.6 and 1.6%, respectively (p < 0.05). There were positive correlations (p < 0.05) between SF and Pmax before (r = 0.86) and after (r = 0.83) the taper phase. Peak lactate concentrations after SF were unaltered before (6.79 +/- 1.2 mM) and after (7.15 +/- 1.8 mM) TP. Results showed that TP improved mean swimming velocity, but not in the same proportion as force after taper, suggesting that there are other factors influencing performance in faster swimming.     

TRAINING LOAD,IMMUNE SYSTEM,UPPER RESPIRATORY SYMPTOMS AND PERFORMANCE IN WELL-TRAINED CYCLISTS THROUGHOUT A COMPETITIVE SEASON

This study aimed to evaluate the leukocyte subset counts, serum immunoglobulin A, performance and upper respiratory symptoms (URS), as well as their interrelationships, of well-trained cyclists for a 29-week training season using monitored loads. The season was divided into three phases: preparatory (nine weeks), first competitive phase (nine weeks) and second competitive phase (11 weeks). The sample consisted of eight well-trained cyclists, aged 18 ± 2 years. Immunological parameters and performance were evaluated during weeks 1 (baseline), 10 (early first competitive phase), 19 (early second competitive phase) and 29 (end of the second competitive phase). The training loads (volume x rating of perceived exertion) were monitored daily while the monitoring of URS was performed every 15 days using the WURSS-44 questionnaire. The data were analyzed using a one-way ANOVA and a Pearson correlation test with the significance level set at p ≤ 0.05. No significant differences were found for training load, leukocyte subset counts or serum immunoglobulin A among the three phases. However, serum immunoglobulin A was 50.9% below the control group values. URS were significantly higher during the preparatory period, and there were significant correlations between URS and training load (strain) in the preparatory period (r = 0.72, p = 0.032) and second competitive phase (r = 0.73, p = 0.036). In conclusion, indicators of training load without a significant change throughout the season did not significantly affect immune parameters measured; however, the increase of strain can cause an increase of upper respiratory symptoms throughout the season, but without loss of performance.     

Small-Sided Games Versus Interval Training in Amateur Soccer Players: Effects on the Aerobic Capacity and the Ability to Perform Intermittent Exercises With Changes of Direction

ABSTRACT: Dellal, A, Varliette, C, Owen, A, Chirico, EN, and Pialoux, V. Small-sided games versus interval training in amateur soccer players: Effects on the aerobic capacity and the ability to perform intermittent exercises with changes of direction. J Strength Cond Res 26(10): 2712-2720, 2012-The purpose of this study was to compare the effects of small-sided games (SSGs) in soccer versus high-intensity intermittent training (HIT) on a continuous aerobic test (Vameval) and the performance in an intermittent test with changes of direction (CODs; 30-15 intermittent fitness test [30-15IFT]). Twenty-two amateur soccer players (mean age ± SD: 26.3 ± 4.7 years) were assigned to 3 different groups for 6 weeks: SSG group (n = 8), HIT group (n = 8), and control group (CG; n = 6). In addition to the usual technical and tactical sessions and competitive games, the SSG group performed 9 sessions of 2 versus 2 and 1 versus 1 SSGs, whereas the HIT group performed 9 sessions of intermittent runs in the form of 30 seconds of effort interspersed with 30 seconds of passive recovery (30s-30s), 15s-15s, and 10s-10s. The HIT and SSG groups showed performance improvements in the Vameval test (5.1 and 6.6%, respectively) and the 30-15IFT intermittent test with CODs (5.1 and 5.8%, respectively), whereas there was no change in the performance of the CG. Players from HIT and SSG groups showed similar increase in their performance in the 30-15IFT and the Vameval tests during the 6-week training period, especially with an increase significantly different to that in a traditional training as in the CG (p < 0.05). This investigation demonstrates that both SSG and HIT interventions are equally effective in developing the aerobic capacity and the ability to perform intermittent exercises with CODs in male amateur soccer players. Furthermore, these 2 methods of training applied during the 6 weeks induce similar effect on the recovery capacity and on the ability to repeat directional changes of 180°. Coaches will now be able to choose between these two methods according to the objective of the training and to optimize the training.     

Gender-related differences in maximum mechanical power output in short-term activities in children and adolescents

The study was designed to examine the gender-related differences in maximum mechanical power output in various short-burst activities during growth. The subject sample consisted of four subgroups: 9 boys (14.11 +/- 0.6 yr), 9 boys (10.67 +/- 0.71 yr), 7 girls (14.29 +/- 0.49 yr), 7 girls (10.57 +/- 0.54 yr). We measured peak power (PP), mean power (MP), fatigue index (FI) during 30-s WAnT, squat jump height (SJH) and power (SJP), and counter movement jump height (CMJH) and power (CMJP), maximum speed over 20-metre distance (S20). Lactation concentration was measured in the 3rd and 5th minutes after the WAnT Ratio normalisation and ANCOVA were used to remove the influence of the differences in muscle (MM) and body mass (BM). Male adolescents had higher absolute values of PP (P < 0.05), MP (P < 0.05) than female. Ratio normalisation showed that boys had higher PP/BM (P < 0.05), PP/MM (P < 0.05), MP/BM (P < 0.05), MP/MM (P < 0.06) than girls. The ANCOVA adjustment for MM showed differences between genders in PP (P < 0.001), MP (P < 0.001), SJH (P < 0.05), SJP (P < 0.05) and CMJP (P < 0.001), whereas the ANCOVA adjustment for BM showed differences only in PP (P < 0.001), MP (P < 0.001). Prepubertal boys had higher absolute values only in SJP (P < 0.05). We concluded that variations in body composition could not be the only key to gender-related differences in power output in short-burst activities.     

Impact of tapering and proactive recovery on young elite rugby union players’ repeated high intensity effort ability

To assess the effects of a taper combined with proactive recovery on the repeated high intensity effort (RHIE) of elite rugby union players, and the possible interaction of pre-taper fatigue and sleep. Eighteen players performed a 3-week intensive training block followed by a 7-day exponential taper combined with a multicomponent recovery strategy. Following the intervention, players were divided into 3 groups (Normal Training: NT, Acute Fatigue: AF or Functional Overreaching: F-OR) based on their readiness to perform prior to the taper. Total sprint time [TST], percentage decrement [%D] and the number of sprints ≥90% of the best [N90] were analyzed to assess performance during a RHIE test. Subjective sleep quality was assessed through the Pittsburg Sleep Quality Index (PSQI) and the Epworth Sleepiness Scale (ESS). No improvement in TST was reported in either NT or F-OR after the taper, whereas AF tended to improve (-1.58 ± 1.95%; p > 0.05; g = -0.20). F-OR players reported baseline PSQI and ESS indicative of sleep disturbance (6.2 ± 2.2 and 10.6 ± 5.4, respectively). AF displayed a small impairment in PSQI during intensive training (11.5 ± 80.6%; p > 0.05; g = 0.20), which was reversed following the taper (-34.6 ± 62.1%; p > 0.05; g = -0.73). Pre-taper fatigue precluded the expected performance benefits of the combined taper and recovery intervention, likely associated with a lack of strictly controlled intensive training block. Poor sleep quality before the intensive training period appeared to predispose the players to developing functional overreaching.     

Training theory and taper: validation in triathlon athletes

This paper defines a training theory with which to predict the effectiveness of various formats of taper in optimizing physical performance from a standardized period of training and taper. Four different taper profiles: step reduction vs exponential (exp) decay and fast vs slow exp decay tapers, were simulated in a systems model to predict performance p(t) resulting from a standard square-wave quantity of training for 28 days. The relative effectiveness of each of the profiles in producing optimal physical improvement above pre-taper criterion physical test standards (running and cycle ergometry) was determined. Simulation showed that an exp taper was better than a step-reduction taper, and a fast exp decay taper was superior to a slow exp decay taper. The results of the simulation were tested experimentally in field trials to assess the correspondence between simulation and real-training criterion physical tests in triathlon athletes. The results showed that the exp taper (tau = 5 days) group made a significantly greater improvement above a pre-taper standard (P < or = 0.05) than the step-reduction taper group in cycle ergometry, and was better, but not significantly so, in a 5-km run. A fast exp taper group B (tau = 4 days) performed significantly better (P < or = 0.05) in maximal, cycle ergometry above a pre-taper training standard than a slow exp taper group A (tau = 8 days) and was improved more, but not significantly so, than group A in a 5-km criterion run. The mean improvement on both physical tests by exp decay taper groups all increased significantly (P < or = 0.05) above their pre-taper training standard. Maximum oxygen uptake increased significantly in a group of eight remaining athletes during 2 weeks of final taper after three athletes left early for final preparations at the race site.     

A comparison of periodization models during nine weeks with equated volume and intensity for strength

The purpose of the present investigation was to determine if significant differences exist among 3 different periodization programs in eliciting changes in strength. Twenty-eight recreationally trained college-aged volunteers (mean +/- SD; 22.29 +/- 3.98) of both genders were tested for bench press, leg press, body fat percentage, chest circumference, and thigh circumference during initial testing. After initial testing, subjects were randomly assigned to 1 of 3 training groups: (a) linear periodization (n = 9), (b) daily undulating periodization (n = 10), or (c) weekly undulating periodization (n = 9). The training regimen for each group consisted of a 9-week, 3-day-per-week program. Training loads were assigned as heavy (90%, 4 repetition maximum [4RM]), medium (85%, 6RM), or light (80%, 8RM) for bench press and leg press exercises. Subjects were familiarized with the CR-10 rated perceived exertion scale and instructed to achieve an 8 or 9 on the final repetition of each set for all other exercises. Subjects were then retested after 4 weeks of training. Training loads were then adjusted according to the new 1RM. Subjects were then retested after 5 more weeks of exercise. For all subjects, significant (p < 0.05) increases in bench press and leg press strength were demonstrated at all time points (T1-T3). No significant differences (p > 0.05) were observed between groups for bench press, leg press, body fat percentage, chest circumference, or thigh circumference at all time points. These results indicate that no separation based on periodization model is seen in early-phase training.     

Body mass, body composition and sleeping metabolic rate before, during and after endurance training

Metabolic rate, more specifically resting metabolic rate (RMR) or sleeping metabolic rate (SMR), of an adult subject is usually expressed as a function of the fat-free mass (FFM). Chronic exercise is thought to increase FFM and thus to increase RMR and SMR. We determined body mass (BM), body composition, and SMR before, during, and after an endurance training programme without interfering with energy intake. The subjects were 11 women and 12 men, aged 37 (SD 3) years and body mass index 22.3 (SD 1.5) kg · m^–2. The endurance training prepared subjects to run a half marathon competition after 44 weeks. The SMR was measured overnight in a respiration chamber. Body composition was measured by hydrostatic weighing. Measurements were performed at 0, 8, 20, 40, and 90 weeks after the start of the training. The BM had decreased from a mean value of 66.6 (SD 6.9) to 65.6 (SD 6.7) kg (P<0.01), fat mass (FM) had decreased from 17.1 (SD 3.9) to 13.5 (SD 3.6) kg (P<0.001), and FFM had increased from 49.5 (SD 7.3) to 52.2 (SD 7.6) kg (P<0.001) at 40 weeks. Mean SMR before and after 40 weeks training was 6.5 (SD 0.7) and 6.2 (SD 0.6) MJ · day^–1 (P<0.05). The decrease in SMR was related to the decrease in BM (r=0.62,P=0.001). At 90 weeks, when most subjects had not trained for nearly a year, BM and SMR were not significantly different from the initial value while FM and FFM had not changed since week 40 of training. In conclusion, it was found that an exercise induced increase in FFM did not result in an increase in SMR. There was an indication of the opposite effect, a decrease in SMR in the long term during training, possibly as a defence mechanism of the body in the maintenance of BM.     

Effect of multiple-load training on the force-velocity relationship

The effect of training with a combination of different loads (multiple-load training) on the force-velocity and force-power relationships was examined with training programs that included maximal isometric contraction (Fmax) and concentric contraction of the elbow flexor muscles. Twenty-one male college students were placed into 3 equal training groups (G(30 + 60), G(30 + 100), and G(30 + 60 + 100)) and performed multiple-load training 3 days per week for 8 weeks. The training load was a set fraction of the maximal isometric strength (% Fmax). The G(30 + 60) group performed 6 repetitions of elbow flexion at 30 and 60% Fmax. The G(30 + 100) group performed 6 repetitions at 30% Fmax and six 5-second Fmax loads. The G(30 + 60 + 100) group performed 4 repetitions at 30 and 60% Fmax and four 5-second Fmax loads. After training, Fmax and maximal velocity significantly increased (p < 0.05) in all 3 training groups. The increases in maximal power were significantly (p < 0.05) different between the G(30 + 60 + 100) group (52.9%) and the G(30 + 100) group (24.2%). These results suggest that multiple-load training programs with 4-6 repetitions are effective for improving muscle power and velocity of the elbow flexors.     

Nonfunctional overreaching during off-season training for skill position players in collegiate American football

The purpose of this study was to determine the performance and hormonal responses to a 15-week off-season training program for American football. Nine skill position players from a National Collegiate Athletic Association (NCAA) Division I-A football team participated as subjects in this study. Following 4 weeks of weight training (phase I), subjects performed weight training concurrently with high-volume conditioning drills (phase II). Phase III consisted of 15 spring football practice sessions executed over a 30-day period. Performance and hormonal changes were assessed prior to phase I, and following phases I, II, and III. Maximal strength was significantly increased (p < 0.05) for all strength tests during phase I. Squat and power clean values decreased following phase II (p < 0.05), with all values returning to baseline upon completion of phase III. Sprinting speed significantly worsened during phase I (p < 0.05), but then returned to baseline during phase III. Vertical jump and agility improved during phase I (p < 0.05), with vertical jump remaining unchanged for the duration of the study and agility returning to baseline following phase II. Testosterone levels decreased during phase II (p < 0.05) prior to returning to baseline levels during phase III. Cortisol and the testosterone/cortisol ratio remained unchanged during the course of the investigation. Even though overtraining did not occur in the current investigation, a significant maladaptation in performance did occur subsequent to phase II. For this particular athletic population, a strength and conditioning program utilizing a reduced training volume-load may prove more effective for improving performance in the future.     

The Road to Gold: Training and Peaking Characteristics in the Year Prior to a Gold Medal Endurance Performance

Purpose

To describe training variations across the annual cycle in Olympic and World Champion endurance athletes, and determine whether these athletes used tapering strategies in line with recommendations in the literature.

Methods

Eleven elite XC skiers and biathletes (4 male; 28±1 yr, 85±5 mL. min⁻¹. kg⁻¹ , 7 female, 25±4 yr, 73±3 mL. min⁻¹. kg⁻¹ ) reported one year of day-to-day training leading up to the most successful competition of their career. Training data were divided into periodization and peaking phases and distributed into training forms, intensity zones and endurance activity forms.

Results

Athletes trained ∼800 h/500 sessions.year⁻¹, including ∼500 h. year⁻¹ of sport-specific training. Ninety-four percent of all training was executed as aerobic endurance training. Of this, ∼90% was low intensity training (LIT, below the first lactate threshold) and 10% high intensity training (HIT, above the first lactate threshold) by time. Categorically, 23% of training sessions were characterized as HIT with primary portions executed at or above the first lactate turn point. Training volume and specificity distribution conformed to a traditional periodization model, but absolute volume of HIT remained stable across phases. However, HIT training patterns tended to become more polarized in the competition phase. Training volume, frequency and intensity remained unchanged from pre-peaking to peaking period, but there was a 32±15% (P<.01) volume reduction from the preparation period to peaking phase.

Conclusions

The annual training data for these Olympic and World champion XC skiers and biathletes conforms to previously reported training patterns of elite endurance athletes. During the competition phase, training became more sport-specific, with 92% performed as XC skiing. However, they did not follow suggested tapering practice derived from short-term experimental studies. Only three out of 11 athletes took a rest day during the final 5 days prior to their most successful competition.     

Muscle mass gain after resistance training is inversely correlated with trunk adiposity gain in postmenopausal women

The aim of this study was to evaluate alterations in trunk adiposity (TA) over 9 months of resistance training (RT) and associate these changes with the hypertrophy of muscle mass (MM) in postmenopausal women (PW). The investigation used a sample that consisted of 22 PW (44-69 years old). The group was subjected to RT (60-80% of 1 repetition maximum) for the total body 3 d · wk(-1). Body composition (dual-energy x-ray absorptiometry) and plasma levels of insulin-like growth factor-1 (IGF-1), follicle-stimulating hormone, E2 (Immulite system), and interleukin-6 (IL-6; enzyme-linked immunosorbent assay) were assessed at the beginning and end of the experiment. After RT, only women who acquired up to 5% TA gained MM, whereas women who acquired >5% TA exhibited increased IL-6 and no MM gain (p < 0.05). The ΔMM was negatively associated with time of menopause (r = -0.45, p < 0.05) and positively associated with baseline IGF-1 (r = 0.47, p < 0.05). Only ΔLE (leg extension) was negatively associated with baseline IL-6 (p < 0.05). Trunk adiposity growth (ΔTF, kilograms) was positively correlated with changes in IL-6 (r = 0.68, p < 0.05). The MM gain was negatively correlated with ΔTF (r = -0.63, p < 0.05) and changes in IL-6 (r = -0.73, p < 0.05). After adjusting all of the confounding variables, only baseline IGF-1 (positively) and changes in IL-6 (negatively) influenced MM, and only the increase in TA influenced IL-6. Our study suggests that increased levels of TA during RT increase IL-6 concentrations, which is a significant negative predictor of MM gain in PW.     

Neovascular niche for human myeloma cells in immunodeficient mouse bone

The interaction with bone marrow (BM) plays a crucial role in pathophysiological features of multiple myeloma (MM), including cell proliferation, chemoresistance, and bone lesion progression. To characterize the MM-BM interactions, we utilized an in vivo experimental model for human MM in which a GFP-expressing human MM cell line is transplanted into NOG mice (the NOG-hMM model). Transplanted MM cells preferentially engrafted at the metaphyseal region of the BM endosteum and formed a complex with osteoblasts and osteoclasts. A subpopulation of MM cells expressed VE-cadherin after transplantation and formed endothelial-like structures in the BM. CD138(+) myeloma cells in the BM were reduced by p53-dependent apoptosis following administration of the nitrogen mustard derivative bendamustine to mice in the NOG-hMM model. Bendamustine maintained the osteoblast lining on the bone surface and protected extracellular matrix structures. Furthermore, bendamustine suppressed the growth of osteoclasts and mesenchymal cells in the NOG-hMM model. Since VE-cadherin(+) MM cells were chemoresistant, hypoxic, and HIF-2α-positive compared to the VE-cadherin(-) population, VE-cadherin induction might depend on the oxygenation status. The NOG-hMM model described here is a useful system to analyze the dynamics of MM pathophysiology, interactions of MM cells with other cellular compartments, and the utility of novel anti-MM therapies.     

Effects of Sprint versus High-Intensity Aerobic Interval Training on Cross-Country Mountain Biking Performance: A Randomized Controlled Trial

Objectives

The current study compared the effects of high-intensity aerobic training (HIT) and sprint interval training (SIT) on mountain biking (MTB) race simulation performance and physiological variables, including peak power output (PPO), lactate threshold (LT) and onset of blood lactate accumulation (OBLA).

Methods

Sixteen mountain bikers (mean ± SD: age 32.1 ± 6.4 yr, body mass 69.2 ± 5.3 kg and VO_2max 63.4 ± 4.5 mL∙kg^-1∙min^-1) completed graded exercise and MTB performance tests before and after six weeks of training. The HIT (7–10 x [4–6 min—highest sustainable intensity / 4–6 min—CR100 10–15]) and SIT (8–12 x [30 s—all-out intensity / 4 min—CR100 10–15]) protocols were included in the participants’ regular training programs three times per week.

Results

Post-training analysis showed no significant differences between training modalities (HIT vs. SIT) in body mass, PPO, LT or OBLA (p = 0.30 to 0.94). The Cohen’s d effect size (ES) showed trivial to small effects on group factor (p = 0.00 to 0.56). The interaction between MTB race time and training modality was almost significant (p = 0.08), with a smaller ES in HIT vs. SIT training (ES = -0.43). A time main effect (pre- vs. post-phases) was observed in MTB race performance and in several physiological variables (p = 0.001 to 0.046). Co-variance analysis revealed that the HIT (p = 0.043) group had significantly better MTB race performance measures than the SIT group. Furthermore, magnitude-based inferences showed HIT to be of likely greater benefit (83.5%) with a lower probability of harmful effects (0.8%) compared to SIT.

Conclusion

The results of the current study suggest that six weeks of either HIT or SIT may be effective at increasing MTB race performance; however, HIT may be a preferable strategy.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT01944865","term_id":"NCT01944865"}}NCT01944865     

Effects of a plyometric training program with and without added load on jumping ability in basketball players

The purpose of this investigation was to examine the effect of a standard plyometric training protocol with or without added load in improving vertical jumping ability in male basketball players. Twenty-seven players were randomly assigned to 3 groups: a control group (no plyometric training), plyometric training group (PG), and loaded plyometric group (LPG, weighted vests 10-11% body mass). Before and after the 10-week training program, all the players were tested for the 5-jump test (5JT), the squat jump (SJ), and the countermovement jump (CMJ). The PG and LPG groups performed 2 and 3 training sessions per week, during the first 3 and the last 7 weeks, respectively. The results showed that SJ, CMJ, and 5JT were significantly improved only in the PG and LPG groups. The best effects for jumps were observed in LPG (p < 0.01), which showed significantly higher gains than the PG (p < 0.05). In conclusion, it appears that loads added to standard plyometric training program may result in greater vertical and horizontal-jump performances in basketball players.     

Muscle Na+-K+-ATPase activity and isoform adaptations to intense interval exercise and training in well-trained athletes.

The Na+ -K+ -ATPase enzyme is vital in skeletal muscle function. We investigated the effects of acute high-intensity interval exercise, before and following high-intensity training (HIT), on muscle Na+ -K+ -ATPase maximal activity, content, and isoform mRNA expression and protein abundance. Twelve endurance-trained athletes were tested at baseline, pretrain, and after 3 wk of HIT (posttrain), which comprised seven sessions of 8 x 5-min interval cycling at 80% peak power output. Vastus lateralis muscle was biopsied at rest (baseline) and both at rest and immediately postexercise during the first (pretrain) and seventh (posttrain) training sessions. Muscle was analyzed for Na+ -K+ -ATPase maximal activity (3-O-MFPase), content ([3H]ouabain binding), isoform mRNA expression (RT-PCR), and protein abundance (Western blotting). All baseline-to-pretrain measures were stable. Pretrain, acute exercise decreased 3-O-MFPase activity [12.7% (SD 5.1), P < 0.05], increased alpha1, alpha2, and alpha3 mRNA expression (1.4-, 2.8-, and 3.4-fold, respectively, P < 0.05) with unchanged beta-isoform mRNA or protein abundance of any isoform. In resting muscle, HIT increased (P < 0.05) 3-O-MFPase activity by 5.5% (SD 2.9), and alpha3 and beta3 mRNA expression by 3.0- and 0.5-fold, respectively, with unchanged Na+ -K+ -ATPase content or isoform protein abundance. Posttrain, the acute exercise induced decline in 3-O-MFPase activity and increase in alpha1 and alpha3 mRNA each persisted (P < 0.05); the postexercise 3-O-MFPase activity was also higher after HIT (P < 0.05). Thus HIT augmented Na+ -K+ -ATPase maximal activity despite unchanged total content and isoform protein abundance. Elevated Na+ -K+ -ATPase activity postexercise may contribute to reduced fatigue after training. The Na+ -K+ -ATPase mRNA response to interval exercise of increased alpha- but not beta-mRNA was largely preserved posttrain, suggesting a functional role of alpha mRNA upregulation.     

Vascular endothelial growth factor-induced migration of multiple myeloma cells is associated with beta 1 integrin- and phosphatidylinositol 3-kinase-dependent PKC alpha activation.

In multiple myeloma (MM), migration is necessary for the homing of tumor cells to bone marrow (BM), for expansion within the BM microenvironment, and for egress into the peripheral blood. In the present study we characterize the role of vascular endothelial growth factor (VEGF) and beta(1) integrin (CD29) in MM cell migration. We show that protein kinase C (PKC) alpha is translocated to the plasma membrane and activated by adhesion of MM cells to fibronectin and VEGF. We identify beta(1) integrin modulating VEGF-triggered MM cell migration on fibronectin. We show that transient enhancement of MM cell adhesion to fibronectin triggered by VEGF is dependent on the activity of both PKC and beta(1) integrin. Moreover, we demonstrate that PKC alpha is constitutively associated with beta(1) integrin. These data are consistent with PKC alpha-dependent exocytosis of activated beta(1) integrin to the plasma membrane, where its increased surface expression mediates binding to fibronectin; conversely, catalytically active PKC alpha-driven internalization of beta(1) integrin results in MM cell de-adhesion. We show that the regulatory subunit of phosphatidylinositol (PI) 3-kinase (p85) is constitutively associated with FMS-like tyrosine kinase-1 (Flt-1). VEGF stimulates activation of PI 3-kinase, and both MM cell adhesion and migration are PI 3-kinase-dependent. Moreover, both VEGF-induced PI 3-kinase activation and beta(1) integrin-mediated binding to fibronectin are required for the recruitment and activation of PKC alpha. Time-lapse phase contrast video microscopy (TLVM) studies confirm the importance of these signaling components in VEGF-triggered MM cell migration on fibronectin.