Vassilios Gourgoulis

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

Chatzinikolaou, A, Fatouros, IG, Gourgoulis, V, Avloniti, A, Jamurtas, AZ, Nikolaidis, MG, Douroudos, I, Michailidis, Y, Beneka, A, Malliou, P, Tofas, T, Georgiadis, I, Mandalidis, D, and Taxildaris, K. Time course of changes in performance and inflammatory responses after acute plyometric exercise. J Strength Cond Res 24(5): 1389-1398, 2010-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.

Effects of a Heavy and a Moderate Resistance Training on Functional Performance in Older Adults

Resistance training can improve strength and functional performance, but there is little information about the effect of training intensity on functional performance in older adults. The purpose of this study was to determine the effect of 12 weeks of heavy (80% of 1 repetition maximum [1RM]) and moderate (60% of 1RM) resistance training on functional performance in healthy, inactive older adults, ages 60–74 years. Volunteer subjects were assigned randomly to a control group (CS, n = 10), heavy resistance training group (HRT, n = 11), or moderate resistance training group (MRT, n = 12) and participated in 12 weeks of strength training, 3 times per week. Performance measurements included 1RM lower-body strength, chair-rising time, walking velocity, stair-climbing time, and flexibility. Significant differences between HRT and MRT were found for 1RM strength of the lower limbs after the training period. Functional performance improved similarly for both HRT and MRT after the training period. Functional performance can be improved significantly with either heavy or moderate resistance training, without significant differences in the effectiveness of the 2 training protocols.

Three-dimensional kinematic analysis of the snatch of elite Greek weightlifters

We investigated the linear kinematics and the change in energy of the barbell and the angular kinematics of the trunk and leg during the snatch technique of 12 elite male Greek weightlifters under competitive conditions after the new weight classification. Two S-VHS cameras operating at 60 Hz were used to record the lifts. The spatial coordinates of selected points were calculated using the direct linear transformation procedure; after digital filtering of the raw data, the angular displacements and angular velocities were calculated for the hip, knee and ankle joints. The following variables were also calculated for the barbell: vertical and horizontal displacement, vertical linear velocity and acceleration, external mechanical work and power output. The results revealed that all weightlifters flexed their knees during the transition phase, independently of their weight category. This indicates that the athletes use the elastic energy produced during the stretch–shortening cycle to enhance their performance. In nine athletes, we found that the barbell trajectory did not cross a vertical reference line that passed through the initial position of the barbell. The vertical linear velocity of the barbell was increased continuously from the beginning of the movement until the second maximum extension of the knee joint, with no notable dip being observed. Regarding the change in energy of the barbell, we found that the mechanical work for the vertical displacement of the barbell in the first pull was significantly greater than the mechanical work in the second pull. In contrast, the estimated average mechanical power output of the athletes during the vertical displacement of the barbell was significantly greater in the second pull than in the first pull. We conclude that the major elements of the snatch technique of elite Greek weightlifters have not been aff ected by the new weight classification.

Unsuccessful vs. Successful Performance in Snatch Lifts: A Kinematic Approach

Gourgoulis, V, Aggeloussis, N, Garas, A, and Mavromatis, G. Unsuccessful vs. successful performance in snatch lifts: a kinematic approach. J Strength Cond Res 23(2): 486-494, 2009-The purpose of the present study was to determine the kinematic characteristics of snatch movements that result in an unsuccessful performance, involving the barbells drop in front of the weightlifter. The sample comprised 7 high-level men weightlifters competing at the international level. Their successful and unsuccessful snatch lifts with the same load were recorded with 2 S-VHS camcorders (60 Hz), and selected points onto the body and the barbell were digitized manually using the Ariel Performance Analysis System. The statistical treatment of the data showed no significant differences (p > 0.05) between successful and unsuccessful lifts in the angular displacement and velocity data of the lower-limb joints, the trajectory and vertical linear velocity of the barbell, or the generated work and power output during the first and second pulls of the lift. Consequently, the general movement pattern of the limbs and the barbell was not modified in unsuccessful lifts in relation to the successful ones. However, significant differences (p < 0.05) were found in the direction of the barbells resultant acceleration vector, suggesting that proper direction of force application onto the barbell is crucial for a successful performance in snatch lifts. Thus, coaches should pay particular attention to the applied force onto the barbell from the first pull.

Kinematic characteristics of the stroke and orientation of the hand during front crawl resisted swimming

Abstract The aim of this study was to examine the acute effect of front crawl sprint resisted swimming with different added resistances on the kinematic characteristics of the stroke and the orientation of the hand. Ten female swimmers swam four maximal trials (25 m) with small, moderate, large, and no added resistance respectively. Four camcorders were used to record the underwater motion of the right hand and digitizing was undertaken using the Ariel Performance Analysis System. Stroke rate, the stroke length, and mean swimming velocity were significantly decreased, whereas the total duration of the stroke and the relative duration of the pull and push phases were significantly increased during resisted swimming. The increase in the total duration of the stroke was accompanied by an increase in absolute pull length, while no alterations were observed in relative pull length or medial-lateral displacements of the hand. Moreover, the mean resultant velocity of the hand, as well as the pitch and the sweepback angles of the hand were not modified. In conclusion, resisted swimming appears to be a specific form of training, at least regarding its acute effect, although long-term effects should be investigated further.

The post-activation potentiation effect on squat jump performance: age and sex effect.

This study examined the post-activation potentiation (PAP) effects on squat jump (SJ) performance and on peak rate of force development (RFDpeak) in preadolescent (10-12 y), adolescents (14-15 y) and adults (20-25 y) males and females. All participants performed a SJ with and without prior conditioning stimulus (PAP and control protocol, respectively), consisting of 3 × 3-second maximal isometric squats. Jump height and RFDpeak of the vertical ground reaction force during SJ were assessed before, and at 20 seconds and at 4 minutes following the conditioning stimulus. The results revealed a different pattern of age-effect on SJ performance within males and females. The RFDpeak significantly increased as a factor of age in both males and females (P < .05). Increase in SJ performance after conditioning stimulus occurred only in men (P < .05), with no effects in teen-males, boys, and female groups. There was a significant PAP effect on RFDpeak in both adult groups (P < .05) and teen-males, with no effects in children. In conclusion, the PAP effects on SJ performance and RFDpeak are age- and sex-dependent; that is PAP appears as a viable method for acutely enhancing SJ performance in men but not in pediatric population.

The effect of leg kick on sprint front crawl swimming

Abstract The aim of this study was to examine the influence of leg kick on the pattern, the orientation and the propulsive forces produced by the hand, the efficiency of the arm stroke, the trunk inclination, the inter-arm coordination and the intra-cyclic horizontal velocity variation of the hip in sprint front crawl swimming. Nine female swimmers swam two maximal trials of 25 m front crawl, with and without leg kick. Four camcorders were used to record the underwater movements. Using the legs, the mean swimming velocity increased significantly. On the contrary, the velocity and the orientation of the hand, the magnitude and the direction of the propulsive forces, as well as the Froude efficiency of the arm stroke were not modified. The hip intra-cyclic horizontal velocity variation was also not changed, while the index of coordination decreased significantly. A significant decrease (13%) was also observed in the inclination of the trunk. Thus, the positive effect of leg kick on the swimming speed, besides the obvious direct generation of propulsive forces from the legs, could probably be attributed to the reduction of the body’s inclination, while the generation of the propulsive forces and the efficiency of the arm stroke seem not to be significantly affected.

Physiological responses during interval training at relative to critical velocity intensity in young swimmers

OBJECTIVES The purpose of this study was to examine the physiological responses on three interval training sets performed at intensities relative to the critical velocity which was calculated from two different combinations of distances using a 2-parameter linear model. METHODS In a controlled repeated measures design, ten male well trained swimmers (age: 15.2 ± 1.2 years) swam 5 × 400-m, 10 × 200-m and 20 × 100-m on separate days with rest to swimming ratio 1:8, aiming to maintain the critical velocity calculated from distances of 50, 100, 200, 400-m (CV(4)) or 200, 400-m (CV(200-400)). RESULTS The sustained velocity on the 5 × 400-m was lower compared to CV(4) and velocity on the 20 × 100-m was higher compared to CV(200-400). The velocity on the 10 × 200-m was kept similar to both CV(4) and CV(200-400) (5 × 400-m: 1.27 ± 0.07 vs. CV(4): 1.33 ± 0.09 ms(-1), p<0.05; 20 × 100-m: 1.32 ± 0.02 vs. CV(200-400): 1.28 ± 0.09 ms(-1), p < 0.05; 10 × 200-m: 1.30 ± 0.10 ms(-1) vs. CV(4) and CV(200-400), p > 0.05). The blood lactate concentration increased after 1200 compared to 400-m (4.45 ± 0.23 vs. 5.82 ± 0.24 mmol l(-1), p < 0.05) and was no different between sets (p > 0.05). Stroke rate and stroke length were not different between and within conditions (p>0.05). Heart rate during the recovery periods was lower in the 5 × 400-m compared to 10 × 200-m and 20 × 100-m training set (p < 0.05). CONCLUSION Interval swimming pace can be adjusted in relation to critical velocity calculated from distances of 200 and 400-m or from distance of 50, 100, 200, 400 m. When the distance of repetitions is increased from 100 to 200 and 400-m the velocity should be reduced by 2% to achieve similar metabolic responses.

The influence of hand paddles on the arm coordination in female front crawl swimmers.

Gourgoulis, V, Aggeloussis, N, Kasimatis, P, Vezos, N, Antoniou, P, and Mavromatis, G. The influence of hand paddles on the arm coordination in female front crawl swimmers. J Strength Cond Res 23(3): 735-740, 2009-The purpose of the research was to determine the influence of hand paddles on the arm coordination in female front crawl swimmers. Ten female swimmers swam at a maximal intensity 25 m without, with small hand paddles (116 cm2), and with large hand paddles (286 cm2). Four S-VHS cameras were used to record the underwater motion of both arms, and the digitizing of selected points onto the subjects body was undertaken using the Ariel Performance Analysis System. The mean swimming velocity, the stroke length, the stroke rate, the relative duration of the separate phases of the stroke, and the index of coordination were then calculated. The index of coordination was defined as the time interval between the propulsive phases of the 2 arms expressed as a percentage of the mean duration of the stroke cycle. The results showed that when the hand paddles were worn, the mean swimming velocity (p < 0.05) and the stroke length (p < 0.05) were significantly increased, whereas the stroke rate was significantly decreased (p < 0.05). When large paddles were worn, the relative duration of the whole propulsive phase was significantly decreased (p < 0.05), and the relative duration of the nonpropulsive phase was significantly increased (p < 0.05). However, the index of coordination was remained unchanged under the 3 measurement conditions (p = 0.895). It was concluded that in front crawl hand-paddled swimming, significant increases of the swimming velocity was not caused by modifications in the pattern of arm coordination. Thus, hand-paddled swimming should not be used as a tool to alter the time sequence of the application of propulsive forces generated from the 2 arms.

The influence of the hand’s acceleration and the relative contribution of drag and lift forces in front crawl swimming

Abstract The aim of this study was to assess the effect of the hand’s acceleration on the propulsive forces and the relative contribution of the drag and lift on their resultant force in the separate phases of the front crawl underwater arm stroke. Ten female swimmers swam one trial of all-out 25-m front crawl. The underwater motion of each swimmer’s right hand was recorded using four camcorders and four periscope systems. Anatomical landmarks were digitised, and the propulsive forces generated by the swimmer’s hand were estimated from the kinematic data in conjunction with hydrodynamic coefficients. When the hand’s acceleration was taken into account, the magnitude of the propulsive forces was greater, with the exception of the mean drag force during the final part of the underwater arm stroke. The mean drag force was greater than the mean lift force in the middle part, while the mean lift force was greater than the mean drag force in the final part of the underwater arm stroke. Thus, swimmers should accelerate their hands from the beginning of their backward motion, press the water with large pitch angles during the middle part and sweep with small pitch angles during the final part of their underwater arm stroke.