The Energy Expenditure Associated With Body-Weight Resistance Exercises of Various Movement Patterns Performed at Different Durations.

ABSTRACT: Poulios, A, Fotiou, C, Draganidis, D, Avloniti, A, Rosvoglou, A, Batrakoulis, A, Tsimeas, P, Papanikolaou, K, Deli, CK, Stampoulis, T, Douroudos, II, Chatzinikolaou, A, Jamurtas, AZ, and Fatouros, IG. The energy expenditure associated with body-weight resistance exercises of various movement patterns performed at different durations. J Strength Cond Res XX(X): 000-000, 2024-Although body-weight resistance exercises (BWRE) are popular and effective for body mass reduction and neuromuscular performance, limited information exists regarding their total energy expenditure (TEE). This study determined the energy cost associated with seven BWRE of different movement patterns plank, push-ups, squat, single-leg squat [SLS], forward lunge [FL], burpees, and jumping jacks [JJ] using 2 different durations (T30: 30-second; T45: 45-second) in 10 healthy young adults using a randomized, 2-trial, crossover, repeated-measures design. The level of significance was set at p ≤ 0.05. The burpees were associated with the highest and the plank with the lowest intensity (rates of perceived exertion [RPE] and mean heart rate [MHR]) and metabolic load (blood lactate [BL] accumulation, metabolic equivalents of task [METs], and excess post-exercise oxygen consumption [EPOC]) in both trials. In T30 and T45, TEE (kcals per minute) was 11.3/12.6 in plank, 18.6/22.0 in FL, 19.8/21.2 in SLS, 19.9/23.2 in squat, 22.0/24.9 in push-ups, 23.1/22.8 in JJ, and 32.2/40.7 in burpees. Although RPE, MHR, BL, and EPOC were comparable among T30 and T45, METs and TEE were greater in T45. These results suggest that TEE of BWRE ranges from ∼11 to 40 kcals·min-1, depending on the movement pattern and the duration of exercise. This information may be valuable for those using BWRE for body-weight management and improvement of strength performance.

In-Season Integrative Neuromuscular Strength Training Improves Performance of Early-Adolescent Soccer Athletes.

Panagoulis, C, Chatzinikolaou, A, Avloniti, A, Leontsini, D, Deli, CK, Draganidis, D, Stampoulis, T, Oikonomou, T, Papanikolaou, K, Rafailakis, L, Kambas, A, Jamurtas, AZ, and Fatouros, IG. In-season integrative neuromuscular strength training improves performance of early-adolescent soccer athletes. J Strength Cond Res 34(2): 516-526, 2020-Although forms of integrative neuromuscular training (INT) are used extensively for injury prevention and treatment, no information exists about its effects on performance of adolescent athletes. We investigated the effects of an in-season INT intervention on performance of early-adolescent players using a 2-group, repeated-measures design. Twenty-eight early adolescents were randomly assigned to a control group (CG, participated only in soccer training, N = 14, 11.4 ± 0.57 years, Tanner stage 2.8 ± 0.6) or an experimental group (INT was added to conventional soccer training, N = 14, 11.2 ± 0.5 years, Tanner stage 2.6 ± 0.5). Integrative neuromuscular training (8 weeks, 3 sessions·wk) aimed to develop core strength, hamstrings eccentric strength, hip/knee musculature, and dynamic stability using body mass exercises, medicine balls, rocker boards, Bosu, stability balls, etc. Ball shooting speed, speed (10, 20-m), change of direction (COD), jumping performance, and strength were measured before and after training. A 2-way repeated-measures ANOVA was used to analyze data. Integrative neuromuscular training improved 10- and 20-m speed (2.52-2.13 and 3.61-3.39 seconds, respectively, p < 0.05), strength (40.1-44.4 kg, p < 0.05), jumping ability (squat jump: 16.3-17.9 cm; countermovement jump: 19.1-20.3 cm, p < 0.05), COD (18.0-17.3 seconds, p < 0.05), and shooting speed (73.8-79.0 km·h, p < 0.05). In the CG, soccer training caused an improvement of smaller magnitude in 10 m and shooting speed (p < 0.05), whereas COD and jumping performance remained unaffected while 20-m speed, COD, and strength deteriorated. These results indicate that an 8-week INT program may induce positive adaptations in performance of early-adolescent soccer players during in-season training, suggesting that INT may be an effective training intervention for this age group.

The Effects of Acute Low-Volume HIIT and Aerobic Exercise on Leukocyte Count and Redox Status.

A single bout of exercise can result in inflammatory responses, increased oxidative stress and upregulation of enzymatic antioxidant mechanisms. Although low-volume high-intensity interval training (HIIT) has become popular, its acute responses on the above mechanisms have not been adequately studied. The present study evaluated the effects of HIIT on hematological profile and redox status compared with those following traditional continuous aerobic exercise (CET). Twelve healthy young men participated in a randomized crossover design under HIIT and CET. In HIIT session, participants performed four 30-sec sprints on a cycle-ergometer with 4 min of recovery against a resistance of 0.375 kg/kg of body mass. CET consisted of 30-min cycling on a cycle-ergometer at 70% of their VO2max. Blood was drawn at baseline, immediately post, 24h, 48h and 72h post-exercise and was analyzed for complete blood count and redox status (thiobarbituric acid reactive substances, [TBARS]; protein carbonyls, [PC]; total antioxidant capacity, [TAC]; catalase and uric acid). White blood cells (WBC) increased after both exercise protocols immediately post-exercise (HIIT: 50% and CET: 31%, respectively). HIIT increased (+22%) PC post-exercise compared to baseline and CET (p < 0.05). HIIT increased TAC immediately post-exercise (16%) and at 24h post-exercise (11%, p < 0.05), while CET increased TAC only post-exercise (12%, p < 0.05) compared to baseline, and TAC was higher following HIIT compared to CET (p < 0.05). Both HIIT and CET increased uric acid immediately post- (21% and 5%, respectively, p < 0.05) and 24h (27% and 5%, respectively, p < 0.05) post-exercise and the rise was greater following HIIT (p < 0.05). There were no significant changes (p > 0.05) for TBARS and catalase following either exercise protocol. Low-volume HIIT is associated with a greater acute phase leukocyte count and redox response than low-volume CET, and this should be considered when an exercise training program is developed and complete blood count is performed for health purposes.

Physical activity may be a potent regulator of bone turnover biomarkers in healthy girls during preadolescence.

This study investigated the effects of different levels of habitual physical activity (PA) assessed by pedometry on bone turnover markers of preadolescent girls according to a cross-sectional experimental design. Sixty prepubertal girls of similar chronological age, bone age, maturity level, and nutritional status were assigned to a low PA (LPA; n = 25), a moderate PA (MPA; n = 17), or a high PA (HPA; n = 18) group. Dual-energy X-ray absorptiometry was used to measure areal bone mineral density (BMD) and bone mineral content (BMC) of the lumbar spine (L2-L4) and dominant hip (femoral neck and trochanter). Blood was collected for the measurement of alkaline phosphatase (ALP), bone-specific ALP (BSAP), procollagen type I N-terminal propeptide (PINP), C-terminal telopeptide of collagen I (CTX), parathyroid hormone (PTH), osteocalcin, thyroid-stimulating hormone, estradiol, testosterone, luteinizing hormone, and follicle-stimulating hormone concentrations. ANOVA revealed that the HPA group (18,695 ± 1244 steps per day) had a lower daily energy intake and body mass than the MPA group (10,774 ± 521 steps per day) and the LPA group (7633 ± 1099 steps per day). The HPA group had higher (P < 0.05) lumbar and hip BMD and hip BMC than the LPA group and higher (P < 0.05) lumbar BMD than the MPA group. The MPA group had higher (P < 0.05) hip BMC than the LPA group. The HPA group had greater (P < 0.05) values of BSAP, PINP, and ALP and lower (P < 0.05) values of PTH and CTX than the LPA group but not the MPA group. A partial correlation analysis (adjusted for body mass index) revealed a positive correlation of steps per day with BMD and BSAP concentration and a negative correlation with PTH and CTX concentration. In conclusion, PA increases BMD and BMC of premenarcheal girls by favoring bone formation over bone resorption.

Protein ingestion preserves proteasome activity during intense aseptic inflammation and facilitates skeletal muscle recovery in humans.

The ubiquitin-proteasome system (UPS) is the main cellular proteolytic system responsible for the degradation of normal and abnormal (e.g. oxidised) proteins. Under catabolic conditions characterised by chronic inflammation, the UPS is activated resulting in proteolysis, muscle wasting and impaired muscle function. Milk proteins provide sulphur-containing amino acid and have been proposed to affect muscle inflammation. However, the response of the UPS to aseptic inflammation and protein supplementation is largely unknown. The aim of this study was to investigate how milk protein supplementation affects UPS activity and skeletal muscle function under conditions of aseptic injury induced by intense, eccentric exercise. In a double-blind, cross-over, repeated measures design, eleven men received either placebo (PLA) or milk protein concentrate (PRO, 4×20 g on exercise day and 20 g/d for the following 8 days), following an acute bout of eccentric exercise (twenty sets of fifteen eccentric contractions at 30°/s) on an isokinetic dynamometer. In each trial, muscle biopsies were obtained from the vastus lateralis muscle at baseline, as well as at 2 and 8 d post exercise, whereas blood samples were collected before exercise and at 6 h, 1 d, 2 d and 8 d post exercise. Muscle strength and soreness were assessed before exercise, 6 h post exercise and then daily for 8 consecutive days. PRO preserved chymotrypsin-like activity and attenuated the decrease of strength, facilitating its recovery. PRO also prevented the increase of NF-κB phosphorylation and HSP70 expression throughout recovery. We conclude that milk PRO supplementation following exercise-induced muscle trauma preserves proteasome activity and attenuates strength decline during the pro-inflammatory phase.

A Comparison of Exercise-Induced Muscle Damage Following Maximal Eccentric Contractions in Men and Boys.

PURPOSE: Research regarding exercise-induced muscle-damage mainly focuses on adults. The present study examined exercise-induced muscle-damage responses in adults compared with children. METHOD: Eleven healthy boys (10-12 y) and 15 healthy men (18-45 y) performed 5 sets of 15 maximal eccentric contractions of the knee extensors. Range of motion (ROM), delayed onset muscle soreness (DOMS) during squat and walking, and peak isometric, concentric and eccentric torque were assessed before, post, 24, 48, 72, and 96 hr postexercise. Creatine kinase (CK) activity was assessed before and 72 hr postexercise. RESULTS: Eccentric exercise resulted in DOMS during squat that persisted for up to 96h in men, and 48 hr in boys (p < .05), and DOMS during walking that persisted for up to 72 hr in men, and 48 hr in boys (p < .01). The ROM was lower in both age groups 48 hr postexercise (p < .001). Isometric (p < .001), concentric (p < .01) and eccentric (p < .01) force decreased post, and up to 48 hr postexercise in men. Except for a reduction in isometric force immediately after exercise, no other changes occurred in boys' isokinetic force. CK activity increased in men at 72 hr postexercise compared with pre exercise levels (p = .05). CONCLUSION: Our data provide further confirmation that children are less susceptible to exercise-induced muscle damage compared with adults.

A 2-Month Linear Periodized Resistance Exercise Training Improved Musculoskeletal Fitness and Specific Conditioning of Navy Cadets.

Vantarakis, A, Chatzinikolaou, A, Avloniti, A, Vezos, N, Douroudos, II, Draganidis, D, Jamurtas, AΖ, Kambas, A, Kalligeros, S, and Fatouros, IG. A 2-month linear periodized resistance exercise training improved musculoskeletal fitness and specific conditioning of navy cadets. J Strength Cond Res 31(5): 1362-1370, 2017-Major objectives of army and navy training are the development of readiness, performance, and injury prevention. Numerous studies have examined the effect of specific strength training (ST) programs on performance of Special Forces and military personnel. Although navy personnel have to address on-board conditions that require the development of strength, agility, speed, and task-specific endurance, there is no information regarding the effects of ST on navy-specific performance. Therefore, the purpose of this study was to investigate the effect of an 8-week ST on performance of navy cadets. Thirty-one cadets of the Hellenic Naval Academy volunteered to participate and were randomly assigned in 2 groups. Cadets in the Experimental Group participated in a linear periodized ST program in addition to their daily training schedule. Cadets in the control group participated only in pre- and post-measurements. Anthropometrics, maximal oxygen consumption, oxygen consumption during a Navy Obstacle Course (NOC), maximum strength in bench press and squat exercises, hand grip strength, repetitions in push-ups and abdominal test, time to complete a 30-m sprint, and time to complete NOC were measured before and after the intervention. A 2-way repeated-measures analysis of variance showed that ST induced favorable changes in bench press and squat 1 repetition maximum, push-ups, abdominal crunches, time to complete 30-m distance, and time to complete the NOC. These results indicate that an additional ST may induce positive alterations on readiness and performance of navy cadets. The study has the approval of university's institutional review board and ethical committee.

Muscle damage, inflammatory, immune and performance responses to three football games in 1 week in competitive male players.

PURPOSE: We examined effects of a three-game, 1-week microcycle (G1, G2, G3) on recovery of performance and inflammatory responses in professional male footballers. METHODS: Players were randomized into an experimental (EXP; N = 20) and a control group (CON; N = 20). Blood was drawn and repeated sprint ability (RSA), muscle soreness and knee range of motion (KJRM) were determined pre- and post-games and during recovery. RESULTS: High-intensity running during G2 was 7-14% less compared to G1 and G3. RSA declined in EXP by 2-9% 3 days post-game with G2 causing the greatest performance impairment. In EXP, game play increased muscle soreness (~sevenfold) compared to CON with G2 inducing the greatest rise, while KJRM was attenuated post-game in EXP compared to CON (5-7%) and recovered slower post G2 and G3 than G1. CK, CRP, sVCAM-1, sP-Selectin and cortisol peaked 48 h post-games with G2 eliciting the greatest increase. Leukocyte count, testosterone, IL-1ß and IL6 responses, although altered 24 h post each game, were comparable among games. Plasma TBARS and protein carbonyls rose by ~50% post-games with G2 eliciting the greatest increase 48 h of recovery. Reduced to oxidized glutathione ratio declined for 24 h post all games with G2 displaying the slowest recovery. Total antioxidant capacity and glutathione peroxidase activity increased (9-56%) for 48 h in response to game play. CONCLUSION: In summary, post-game performance recovery and inflammatory adaptations in response to a three-game weekly microcycle displayed a different response pattern, with strong indications of a largest physiological stress and fatigue after the middle game that was preceded by only a 3-day recovery.

The Acute Effects of Static Stretching on Speed and Agility Performance Depend on Stretch Duration and Conditioning Level.

Avloniti, A, Chatzinikolaou, A, Fatouros, IG, Avloniti, C, Protopapa, M, Draganidis, D, Stampoulis, T, Leontsini, D, Mavropalias, G, Gounelas, G, and Kambas, A. The acute effects of static stretching on speed and agility performance depend on stretch duration and conditioning level. J Strength Cond Res 30(10): 2767-2773, 2016-Although static stretching (SS) is an integral part of physical preparation before training and competition, its usefulness in regards to power performance improvement has been questioned. The aim of this study was to investigate the effect of 6 SS durations on speed and agility performance. According to a cross-over design, 34 trained men (age, 20.5 ± 1.4 years; height, 1.81 ± 0.2 m; weight, 77.2 ± 2.6 kg; body fat, 8.2 ± 2.6%) participated in a control session (no stretch) and 6 experimental conditions (10, 15, 20, 30, 40, and 60 seconds) performed in a randomized order. Performance in speed (10 and 20 m) and agility (T-test) was measured after the control and experimental conditions. Static stretching, consisting of stretches for hip extensors, hip adductors, knee extensors, knee flexors, and ankle sole flexors, was performed after light cardiovascular exercise (8 minutes). A 1-way repeated-measures analysis of variance showed that speed was improved only by SS of short duration (15/20 seconds), whereas agility remained unaffected by all SS trials. When participants' speed and agility level was taken into account, it was revealed that only those of moderate performance demonstrated an improved speed (in 15- and 20-second trials) and agility (in 10- and 15-second trials) performance. These results suggest that short-duration SS protocols induce an acute improvement of speed and agility performance, whereas longer-duration SS protocols have neither positive nor negative effect. Furthermore, it seems that individuals of lower speed and agility performance level are more likely to benefit by a short-duration SS protocol.

Antioxidation improves in puberty in normal weight and obese boys, in positive association with exercise-stimulated growth hormone secretion.

BACKGROUND: Oxidative stress is associated with obesity while the evidence for the role of GH in pro- and antioxidation is inconclusive. This study investigates the relationships between growth hormone (GH), pro- and antioxidation in relation to obesity and puberty before and after an acute bout of exercise. METHODS: In this case-control study, 76 healthy normal-weight and obese, prepubertal and pubertal boys underwent a blood sampling before and immediately after an aerobic exercise bout until exhaustion at 70% maximal oxygen consumption. Markers of prooxidation (thiobarbituric acid reactive substances (TBARS) and protein carbonyls (PCs)) and antioxidation (glutathione (GSH), oxidized glutathione disulfide (GSSG), GSH/GSSG ratio, glutathione peroxidase (GPX), catalase, and total antioxidant capacity (TAC)) and hormones (GH, insulin-like growth factor (IGF)-1, IGF-BP-3, luteinizing hormone, follicle-stimulating hormone, and testosterone) were measured. RESULTS: Baseline and postexercise TBARS and PCs were greater, while baseline GSH, GSH/GSSG ratio, GPX, and TAC were lower in obese than that in normal-weight participants. In all participants, waist was the best negative and positive predictor for postexercise GPX and TBARS, respectively. Baseline TAC was greater in pubertal than that in pre-pubertal participants. In all participants, baseline GH was the best negative predictor for postexercise PCs. Significant positive linear correlation exists between the exercise-associated GH, and GSSG increases in pubertal normal-weight boys. CONCLUSIONS: Higher prooxidation and lower antioxidation were observed in obese boys, while antioxidation improves with puberty and postexercise, paralleling GH accentuated secretion.

Iron status markers are only transiently affected by a football game.

We examined the temporal variation of iron's status markers during a 60 h period following a football game. Thirty-four male football players were randomly assigned to a control group (CG, N = 14, participated only in measurements and training) or an experimental group (EG, N = 20, took part in a football game one week after the completion of the competitive season). All participants trained regularly for two consecutive days after the game. Training and game load was monitored with high time-resolution global positioning system (GPS) devices. Blood samples were collected and muscle damage markers and repeated sprint ability (RSA) were assessed pre-game and at 2 h, 12 h 36 h and 60 h post-game. No changes were noted in CG. Iron concentration decreased (P < 0.05) 2 h post-game and normalised thereafter whereas total iron binding capacity increased (P < 0.05) 12-60 h of recovery (P < 0.05). Erythrocytes, haemoglobin (HGB) concentration, plasma volume, haematocrit, mean cell volume, mean cell HGB, mean cell HGB concentration, red cell width-SD, red cell width-CV, ferritin concentration and transferrin saturation remained unaltered during the intervention period. Creatine kinase activity and muscle soreness increased (P < 0.05) throughout recovery in EG. RSA declined (P < 0.05) until 36 h of recovery and normalised thereafter. Our data demonstrate that iron status markers are only transiently affected by a football game.

Pedometer determined physical activity and obesity prevalence of Greek children aged 4-6 years.

BACKGROUND: Pre-school age is important for developing healthy attitudes towards physical activity (PA). However, research on pre-schoolers' pedometer-determined PA is limited. AIM: To describe pre-schoolers' ambulatory activity; investigate step count differences in respect to Body Mass Index (BMI) categories and examine the prevalence of obesity. SUBJECTS AND METHODS: Pre-school aged children (n = 250; 5.5 ± 0.4 years) from Komotini (Greece) wore Omron HJ-720IT-E2 pedometers for 10 consecutive days. Height and weight were measured and BMI was calculated. RESULTS: Three-way repeated measures ANOVAs revealed that children performed more steps on weekdays than during weekends (p < 0.001) and during leisure time than school (p < 0.001). Significant differences appeared between normal and obese children's counts on weekdays (p < 0.001), weekend days (p < 0.05), during school (p < 0.001), after school (p < 0.005) and in weekly steps (p < 0.005). No gender differences were detected. Moreover, according to a sample t-test analysis, children's daily steps were significantly different from the 10,000 steps/day guideline, while obesity prevalence was 15.6%. CONCLUSION: School-based ambulatory activity is lower than after school ambulatory activity, independent of BMI-category and gender, although obese children demonstrated fewer steps. Taking into account the high rate of both the obesity prevalence and children not meeting the 10,000 steps/day guideline, the need for preventive policies becomes obvious.

The microcycle of inflammation and performance changes after a basketball match.

Basketball incorporates intense eccentric muscle activity that induces muscle microtrauma and an inflammatory response. This study investigated time-dependent inflammatory and performance responses during a weekly microcycle after a basketball match. Twenty elite-standard players underwent a trial that comprised a match followed by a 6-day simulated in-season microcycle. The trial was preceded by a control condition that did not have a match. Blood sampling and tests of maximal-intensity exercise performance and muscle damage occurred before each condition, immediately after the match and daily thereafter for 6 consecutive days. The match induced marked increases in heart rate, lactate, ammonia, glucose, non-esterified fatty acids and triglycerides. Performance deteriorated for 24-48 h after the match, whereas knee flexor and extensor soreness increased for 48 and 24 h post-match, respectively. Inflammatory (leukocytes, C-reactive protein, creatine kinase activity, adhesion molecules, cortisol, uric acid and cytokines) and oxidative stress (malondialdehyde, protein carbonyls, oxidised glutathione, antioxidant capacity, catalase and glutathione peroxidase) markers increased for ~24 h and subsided thereafter. Reduced glutathione declined for 24 h after exercise. These results suggest that a basketball match elicits moderate and relatively brief (~24-48 h) inflammatory responses, is associated with marked but short-lived performance deterioration, but is less stressful than other intermittent-type sports.

A microcycle of inflammation following a team handball game.

This study investigated the time-course of performance and inflammatory responses during a simulated 6-day in-season microcycle following a team handball (TH) game. Twenty-four handball players participated in a 1-week control trial and in an experimental trial (TH game participation followed by a 6-day training microcycle). Concentrations of lactate, glucose, glycerol, triglycerides, nonesterified fatty acids (NEFAs), and ammonia were measured pregame and postgame. Heart rate (HR) was monitored during the game. Performance (jumping, speed, agility, line-drill testing, and strength), muscle damage (knee range of motion [ROM], knee extensors/flexors delayed onset muscle soreness [DOMS], and creatine kinase activity [CK]), inflammatory (leukocyte count, C-reactive protein, interleukins 1ß and 6 [IL-1ß and IL-6], soluble vascular adhesion molecule 1 [sVCAM-1], p-selectin, uric acid, cortisol, and testosterone), and oxidative stress (malondialdehyde [MDA], protein carbonyls [PC], reduced [GSH] and oxidized glutathione [GSSG], total antioxidant capacity (TAC), catalase, glutathione peroxidase activity [GPX]) markers were determined pregame, postgame, and daily for 6 consecutive days postgame. The game induced a marked rise of HR (∼170 b·min-1), lactate (∼8-fold), glycerol (60%), NEFA (105%), and ammonia (∼62%). Performance deteriorated until 24 hours postgame. Knee ROM decreased (3-5%), whereas DOMS and CK increased (3- to 5-fold and 80-100%, respectively) 24 hours postgame. Leukocyte count, IL-1ß, IL-6, cortisol, MDA, PC, and catalase increased only immediately postgame. C-reactive protein and uric acid increased at 24 hours; sVCAM-1, GSSG, and GPX peaked postgame and remained elevated for 24 hours. The GSH declined until 24 hours postgame. Results suggest that a TH game represents a strong metabolic challenge and induces a short-lived and modest inflammatory response that may affect performance for as long as 24 hours postgame.

The time-frame of acute resistance exercise effects on football skill performance: the impact of exercise intensity.

The purpose of this study was to determine the recovery rate of football skill performance following resistance exercise of moderate or high intensity. Ten elite football players participated in three different trials: control, low-intensity resistance exercise (4 sets, 8-10 repetitions/set, 65-70% 1 repetition maximum [1RM]) and high-intensity resistance exercise (4 sets, 4-6 repetitions/set, 85-90% 1RM) in a counterbalanced manner. In each experimental condition, participants were evaluated pre, post, and at 24, 48, 72 h post exercise time points. Football skill performance was assessed through the Loughborough Soccer Passing Test, long passing, dribbling, shooting and heading. Delayed onset muscle soreness, knee joint range of motion, and muscle strength (1RM) in squat were considered as muscle damage markers. Blood samples analysed for creatine kinase activity, C-reactive protein, and leukocyte count. Passing and shooting performance declined (P < 0.05) post-exercise following resistance exercise. Strength declined post-exercise following high-intensity resistance exercise. Both trials induced only a mild muscle damage and inflammatory response in an intensity-dependent manner. These results indicate that football skill performance is minimally affected by acute resistance exercise independent of intensity suggesting that elite players may be able to participate in a football practice or match after only 24 h following a strength training session.

Plyometrics' trainability in preadolescent soccer athletes.

Plyometric training (PT) is a widely used method to improve muscle ability to generate explosive power. This study aimed to determine whether preadolescent boys exhibit plyometric trainability or not. Forty-five children were randomly assigned to either a control (CG, N = 21, 10.6 ± 0.5 years; participated only in regular soccer practice) or a plyometric training group (PTG, N = 24, 10.6 ± 0.6 years; participated in regular soccer practice plus a plyometric exercise protocol). Both groups trained for 12 weeks during the in-season period. The PT exercises (forward hopping, lateral hopping, shuffles, skipping, ladder drills, skipping, box jumps, low-intensity depth jumps) were performed twice a week. Preadolescence was verified by measuring Tanner stages, bone age, and serum testosterone. Speed (0-10, 10-20, 20-30 m), leg muscle power (static jumping, countermovement jumping, depth jumping [DJ], standing long jump [SLJ], multiple 5-bound hopping [MB5]), leg strength (10 repetition maximum), anaerobic power (Wingate testing), and soccer-specific performance (agility, kicking distance) were measured at baseline, midtraining, and posttraining. The CG caused only a modest (1.2-1.8%) increase in speed posttraining. The PTG induced a marked (p < 0.05) improvement in all speed tests (1.9-3.1% at midtraining and 3-5% at posttraining) and vertical jump tests (10-18.5% at midtraining and 16-23% at posttraining), SLJ (2.6% at midtraining and 4.2% at posttraining), MB5 (14.6% at midtraining and 23% at posttraining), leg strength (15% at midtraining and 28% at posttraining), agility (5% at midtraining and 23% at posttraining), and kicking distance (13.6% at midtraining and 22.5% at posttraining). Anaerobic power remained unaffected in both groups. These data indicate that (a) prepubertal boys exhibit considerable plyometric trainability, and (b) when soccer practice is supplemented with a PT protocol, it leads to greater performance gains.

Elite premenarcheal rhythmic gymnasts demonstrate energy and dietary intake deficiencies during periods of intense training.

This study determined dietary intake and energy balance of elite premenarcheal rhythmic gymnasts during their preseason training. Forty rhythmic gymnasts and 40 sedentary age-matched females (10-12 yrs) participated in the study. Anthropometric profile and skeletal ages were determined. Dietary intake and physical activity were assessed to estimate daily energy intake, daily energy expenditure, and resting metabolic rate. Groups demonstrated comparable height, bone age, pubertal development, resting metabolic rate. Gymnasts had lower body mass, BMI, body fat than age-matched controls. Although groups demonstrated comparable daily energy intake, gymnasts exhibited a higher daily energy expenditure resulting in a daily energy deficit. Gymnasts also had higher carbohydrate intake but lower fat and calcium intake. Both groups were below the recommended dietary allowances for fiber, water, calcium, phosphorus and vitamin intake. Gymnasts may need to raise their daily energy intake to avoid the energy deficit during periods of intense training.

Acute resistance exercise results in catecholaminergic rather than hypothalamic-pituitary-adrenal axis stimulation during exercise in young men.

Exercise is a paradigm of a stress situation. The adaptive response to stressors comprises the activation of the hypothalamic-pituitary-adrenal (HPA) axis and components of the autonomic sympathetic system. An aseptic inflammatory reaction is triggered by exercise, involving the stimulation of the so-called proinflammatory cytokines, such as tumor necrosis factor α (TNFα), interleukin-1 (IL-1), and IL-6. The anti-inflammatory cytokines IL-2, IL-8, and IL-10 increase moderately during resistance exercise. To investigate the effect of a short bout of resistance exercise on components of the stress and inflammatory responses during the exercise period, 17 healthy, young, untrained male volunteers were studied during 3 equal consecutive cycles of resistance exercises of 30 min total duration. Blood sampling was performed at baseline and at the end of each cycle. Lactate, cortisol, catecholamines (epinephrine, norepinephrine), IL-1α, IL-1ß, IL-2, IL-6, IL-8, IL-10, epidermal growth factor (EGF), and monocyte chemotactic protein-1 (MCP-1) were measured at all time-points. Circulating levels of catecholamines and lactate increased significantly (P < 0.05) whereas cortisol did not. During the time course of the exercise, circulating levels of TNFα, IL-2, and EGF increased, whereas MCP-1 decreased significantly. IL-1α, IL-1ß, IL-6, IL-8, and IL-10 levels did not change significantly. Statistically significant positive linear correlations were found between areas under the curve for increases in levels of IL-2 and TNFα, TNFα and cortisol, as well as epinephrine and norepinephrine. We conclude that acute resistance exercise results in catecholaminergic, but not HPA axis stimulation during exercise, in parallel with a mild inflammatory reaction. The absence of a major inflammatory reaction and of a cortisol increase during acute resistance exercise makes this a good candidate for the exercise of sedentary individuals.

Time course of changes in performance and inflammatory responses after acute plyometric exercise.

The objectives of the present investigation were to study the inflammatory and performance responses after an acute bout of intense plyometric exercise during a prolonged recovery period. Participants were randomly assigned to either an experimental group (P, n = 12) that performed intense plyometric exercises or a control group (C, n = 12) that rested. The delayed onset of muscle soreness (DOMS), knee range of motion (KROM), creatine kinase (CK) and lactate dehydrogenase (LDH) activities, white blood cell count, C reactive protein (CRP), uric acid (UA), cortisol, testosterone, IL-6, IL-1b strength (isometric and isokinetic), and countermovement (CMJ) and static (SJ) jumping performance were measured at rest, immediately postexercise and at 24, 48, 72, 96, and 120 hours of recovery. Lactate was measured at rest and postexercise. Strength remained unchanged throughout recovery, but CMJ and SJ declined (p < 0.05) by 8-20%. P induced a marked rise in DOMS, CK, and LDH (peaked 24-48 hours postexercise) and a KROM decline. An acute-phase inflammatory response consisting of leukocytosis (postexercise and at 24 hours), an IL-6, IL-1b, CRP, and cortisol elevation (during the first 24 hours of recovery) and a delayed increase of UA (peaked at 48 hours) and testosterone (peaked at 72 hours) was observed in P. The results of this investigation indicate that performing an acute bout of intense plyometric exercise may induce a short-term muscle damage and marked but transient inflammatory responses. Jumping performance seems to deteriorate for as long as 72 hours postexercise, whereas strength appears to remain unchanged. The acute-phase inflammatory response after a plyometric exercise protocol appears to follow the same pattern as in other exercise models. These results clearly indicate the need of sufficient recovery between successive plyometric exercise training sessions.

Intradialytic Cardiovascular Exercise Training Alters Redox Status, Reduces Inflammation and Improves Physical Performance in Patients with Chronic Kidney Disease.

Redox status (RS) perturbations and inflammation are fundamental features of chronic kidney disease (CKD) that are substantially exacerbated in end-stage renal disease (ESRD). This study aimed at investigating the efficacy of a 6-month intradialytic exercise training program on RS, inflammation and physical performance in patients with ESRD. Twenty hemodialysis (HD) patients (17 males, three females) were randomly assigned to either an intradialytic training (bedside cycling) group (TR; n = 10) or a control group (CON; n = 10) for 6 months. Anthropometrics [body mass and height, body mass index (BMI), body composition], physical performance (VO2peak), functional capacity [North Staffordshire Royal Infirmary (NSRI) walk test, sit-to-stand test (STS-60)], quality of life (short form-36 (SF-36) as well as RS [thiobarbituric acid reactive substances (TBARS), protein carbonyls (PC), reduced (GSH) and oxidized (GSSG) glutathione, GSH/GSSG, total antioxidant capacity (TAC), catalase activity (CAT)] and high-sensitivity C-reactive protein (hs-CRP) were assessed at baseline and after the 6-month intervention. Peak oxygen consumption (VO2peak) increased by 15% only in TR (p < 0.01). Performance in NSRI, STS-60 and SF-36 improved by 4-13% only in TR (p < 0.01). Exercise training reduced TBARS (by 28%), PC (by 31%) and hs-CRP (by 15%), and elevated GSH (by 52%), GSH/GSSG (by 51%), TAC (by 59%) and CAT (by 15%) (p < 0.01). These findings suggest that engagement in chronic intradialytic cardiovascular exercise alters RS, reduces inflammation and improves performance in patients with ESRD.