Spyridon Methenitis

Body composition analysis in late-onset Pompe disease.

Pompe disease is an inherited metabolic disorder caused by α-glycosidase deficiency. The adult onset form is mainly characterized by progressive proximal muscle weakness and respiratory dysfunction. The aim of the present study is to evaluate body composition in adult patients before and after enzyme replacement therapy (ERT). Body composition was examined at baseline by means of dual x-ray absorptiometry (DXA) in nine adult patients and after different time periods in six of them who received ERT. Total BMD (bone mineral density) was initially mildly decreased in two patients, while femoral neck BMD was decreased in five patients. On the other hand fat mass was increased in the majority of patients, while body mass index (BMI) was high in four. ERT administration did not seem to induce obvious BMD changes in any patient. Conclusively, the greater femoral neck BMD involvement may be attributed to the lower mechanical load applied by the selectively weakened muscles, whereas the increased fat mass may be the result of metabolic and nutritional derangement.

Rate of Force Development, Muscle Architecture, and Performance in Young Competitive Track and Field Throwers.

Abstract Zaras, ND, Stasinaki, A-NE, Methenitis, SK, Krase, AA, Karampatsos, GP, Georgiadis, GV, Spengos, KM, and Terzis, GD. Rate of force development, muscle architecture, and performance in young competitive track and field throwers. J Strength Cond Res 30(1): 81–92, 2016—The rate of force development (RFD) is an essential component for performance in explosive activities, although it has been proposed that muscle architectural characteristics might be linked with RFD and power performance. The purpose of the study was to investigate the relationship between RFD, muscle architecture, and performance in young track and field throwers. Twelve young track and field throwers completed 10 weeks of periodized training. Before (T1) and after (T2) training performance was evaluated in competitive track and field throws, commonly used shot put tests, isometric leg press RFD, 1 repetition maximum (1RM) strength as well as vastus lateralis architecture and body composition. Performance in competitive track and field throwing and the shot put test from the power position increased by 6.76 ± 4.31% (p < 0.001) and 3.58 ± 4.97% (p = 0.019), respectively. Rate of force development and 1RM strength also increased (p ⩽ 0.05). Vastus lateralis thickness and fascicle length increased by 5.95 ± 7.13% (p = 0.012) and 13.41 ± 16.15% (p = 0.016), respectively. Significant correlations were found at T1 and T2, between performance in the shot put tests and both RFD and fascicle length (p ⩽ 0.05). Close correlations were found between RFD, muscle thickness, and fascicle length (p ⩽ 0.05). Significant correlations were found between the % changes in lean body mass and the % increases in RFD. When calculated together, the % increase in muscle thickness and RFD could predict the % increase in shot put throw test from the power position (p = 0.019). These results suggest that leg press RFD may predict performance in shot put tests that are commonly used by track and field throwers.

Effects of Tapering With Light vs. Heavy Loads on Track and Field Throwing Performance

Abstract Zaras, ND, Stasinaki, A-NE, Krase, AA, Methenitis, SK, Karampatsos, GP, Georgiadis, GV, Spengos, KM, and Terzis, GD. Effects of tapering with light vs. heavy loads on track and field throwing performance. J Strength Cond Res 28(12): 3484–3495, 2014—The purpose of the study was to investigate the effects of power training with light vs. heavy loads during the tapering phases of a double periodized training year on track and field throwing performance. Thirteen track and field throwers aged 16–26 years followed 8 months of systematic training for performance enhancement aiming at 2 tapering phases during the winter and the spring competition periods. Athletes performed tapering with 2 different resistance training loads (counterbalanced design): 7 athletes used 30% of 1 repetition maximum (1RM) light-load tapering (LT), and 6 athletes used the 85% of 1RM heavy-load tapering (HT), during the winter tapering. The opposite was performed at the spring tapering. Before and after each tapering, throwing performance, 1RM strength, vertical jumping, rate of force development (RFD), vastus lateralis architecture, and rate of perceived exertion were evaluated. Throwing performance increased significantly by 4.8 ± 1.0% and 5.6 ± 0.9% after LT and HT, respectively. Leg press 1RM and squat jump power increased more after HT than LT (5.9 ± 3.2% vs. −3.4 ± 2.5%, and 5.1 ± 2.4% vs. 0.9 ± 1.4%, respectively, p ⩽ 0.05). Leg press RFD increased more in HT (38.1 ± 16.5%) compared with LT (−2.9 ± 6.7%), but LT induced less fatigue than HT (4.0 ± 1.5 vs. 6.7 ± 0.9, p ⩽ 0.05). Muscle architecture was not altered after either program. These results suggest that performance increases similarly after tapering with LT or HT in track and field throwers, but HT leads to greater increases in strength, whole body power, and RFD.

Muscle Fiber Conduction Velocity, Muscle Fiber Composition, and Power Performance

PURPOSE The aim of this study was to explore the relationship between muscle fiber conduction velocity (MFCV), fiber type composition, and power performance in participants with different training background. METHODS Thirty-eight young males with different training background participated: sedentary (n = 10), endurance runners (n = 9), power trained (n = 10), and strength trained (n = 9). They performed maximal countermovement jumps (CMJ) and maximal isometric leg press for the measurement of the rate of force development (RFD). Resting vastus lateralis MFCV was measured with intramuscular microelectrodes on a different occasion, whereas muscle fiber type and cross-sectional area (CSA) of vastus lateralis were evaluated through muscle biopsies 1wk later. RESULTS MFCV, CMJ power, RFD, and % CSA of type II and type IIx fibers were higher for the power-trained group (P < 0.001). No difference was found between sedentary participants and endurance runners in these variables, but both of these groups performed worse than strength/power participants. Close correlations were found between MFCV and fiber CSA as well as the % CSA of all fiber types as well as with RFD and CMJ power (r = 0.712-0.943, P < 0.005). Partial correlations revealed that the % CSA of IIx fibers dictates a large part of the correlation between MFCV and RFD, power performance. Significant models for the prediction of the % CSA of type IIa and type II as well as the CSA of all muscle fibers based upon MFCV, RFD, and CMJ were revealed (P = 0.000). CONCLUSION MFCV is closely associated with muscle fiber % CSA. RFD and jumping power are associated with the propagation of the action potentials along the muscle fibers. This link is regulated by the size and the distribution of type II, and especially type IIx muscle fibers.

Role of Muscle Morphology in Jumping, Sprinting, and Throwing Performance in Participants With Different Power Training Duration Experience

Abstract Methenitis, SK, Zaras, ND, Spengos, KM, Stasinaki, A-NE, Karampatsos, GP, Georgiadis, GV, and Terzis, GD. Role of muscle morphology in jumping, sprinting, and throwing performance in participants with different power training duration experience. J Strength Cond Res 30(3): 807–817, 2016—The aim of the study was to examine the correlation between muscle morphology and jumping, sprinting, and throwing performance in participants with different power training duration experience. Thirty-six power-trained young men were assigned to 3 groups according to the length of their power training: less experienced (<1 year), moderately experienced (1–3 years), and experienced (4–7 years). All participants performed countermovement and squat jumps, 60-m sprint, and shot throws twice. Lean body mass (LBM) was evaluated with dual-energy x-ray absorptiometry and thigh muscle cross-sectional area (CSA) with anthropometry. The vastus lateralis architecture and fiber type composition were evaluated with ultrasonography and muscle biopsies, respectively. When all subjects were considered as 1 group (n = 36), jumping performance was correlated with LBM, fascicle length, and type II fiber CSA; sprinting performance was correlated with estimated thigh muscle CSA alone; and shot throwing was correlated with LBM and type I, IIA fiber CSA. In the least experienced group, the LBM of the lower extremities was the most significant contributor for power performance, whereas in the moderately experienced group, the LBM, architectural properties, and type II fiber percentage CSA were the most significant contributors. For the experienced group, fascicle length and type II fiber percentage CSA were the most significant factors for power performance. These data suggest that jumping performance is linked with muscle morphology, regardless of strength or power training. The vastus lateralis muscle morphology could only partially explain throwing performance, whereas it cannot predict sprinting performance. Power performance in experienced participants rely more on the quality of the muscle tissue rather than the quantity.

Intramuscular fiber conduction velocity, isometric force and explosive performance.

Abstract Conduction of electrical signals along the surface of muscle fibers is acknowledged as an essential neuromuscular component which is linked with muscle force production. However, it remains unclear whether muscle fiber conduction velocity (MFCV) is also linked with explosive performance. The aim of the present study was to investigate the relationship between vastus lateralis MFCV and countermovement jumping performance, the rate of force development and maximum isometric force. Fifteen moderately-trained young females performed countermovement jumps as well as an isometric leg press test in order to determine the rate of force development and maximum isometric force. Vastus lateralis MFCV was measured with intramuscular microelectrodes at rest on a different occasion. Maximum MFCV was significantly correlated with maximum isometric force (r = 0.66, p < 0.01), nevertheless even closer with the leg press rate of force development at 100 ms, 150 ms, 200 ms, and 250 ms (r = 0.85, r = 0.89, r = 0.91, r = 0.92, respectively, p < 0.01). Similarly, mean MFCV and type II MFCV were better correlated with the rate of force development than with maximum isometric leg press force. Lower, but significant correlations were found between mean MFCV and countermovement jump power (r = 0.65, p < 0.01). These data suggest that muscle fiber conduction velocity is better linked with the rate of force development than with isometric force, perhaps because conduction velocity is higher in the larger and fastest muscle fibers which are recognized to contribute to explosive actions.

Nutritional Routine of Tae Kwon Do Athletes Prior to Competition: What Is the Impact of Weight Control Practices?

ABSTRACT Objective: The purpose of the present study was to investigate and assess the common dietary and weight management strategies of Tae Kwon Do (TKD) athletes prior to national competitions, as well as to examine the relationships between these strategies and body weight reduction and sensation of physical condition. Methods: Sixty (n = 60) TKD athletes, 23 women (19.4 ± 2.9 years) and 37 men (20.4 ± 3.6 years), with at least 12.1 ± 3.1 years of experience, participated in the present study. The athletes recorded their dietary intake and physical activity for 3 training days and on a competition day. Bioelectrical impedance was used for body composition estimation. Results: Male athletes consumed 1918 ± 685 kcal/24 hours and 1974 ± 669 kcal/24 hours on training and competition days, respectively, and women 1814 ± 446 kcal/24 hours and 1700 ± 439 kcal/24 hours. TKD athletes had significant negative energy balance (48.6% ± 17.8% to 60.3% ± 26.9%; p < 0.05), with the majority of macro- and micronutritional elements being lower than the recommended values, with significant differences between them, as well as within groups, between weekdays and weekend days (p < 0.05). Females lost most of their weight 2 weeks before the games (3.50 ± 1.00 kg), and males lost most of their weight 3 weeks before (3.16 ± 2.48 kg). The majority of TKD athletes were guided by their coaches for weight management strategies. No significant correlations were found between any body composition variable, weight loss, and any nutritional intake at any time point (p > 0.05). Conclusions: These data suggest that the methods of TKD athletes for rapid weight loss are guided by unspecialized professionals, leading to significant malnutrition, because certain deficiencies in both macro- and micronutrient content are present, with no guaranteed specific reduction of their body mass.

The Importance of Lean Body Mass for the Rate of Force Development in Taekwondo Athletes and Track and Field Throwers

The rate of force development (RFD) is vital for power athletes. Lean body mass (LBM) is considered to be an essential contributor to RFD, nevertheless high RFD may be achieved by athletes with either high or low LBM. The aim of the study was to describe the relationship between lower-body LBM and RFD, and to compare RFD in taekwondo athletes and track and field (T&F) throwers, the latter having higher LBM when compared to taekwondo athletes. Nine taekwondo athletes and nine T&F throwers were evaluated for countermovement jumping, isometric leg press and leg extension RFD, vastus lateralis (VL), and medial gastrocnemius muscle architecture and body composition. Lower body LBM was correlated with RFD 0–250 ms (r = 0.81, p = 0.016). Taekwondo athletes had lower LBM and jumping power per LBM. RFD was similar between groups at 30–50 ms, but higher for throwers at 80–250 ms. RFD adjusted for VL thickness was higher in taekwondo athletes at 30 ms, but higher in throwers at 200–250 ms. These results suggest that lower body LBM is correlated with RFD in power trained athletes. RFD adjusted for VL thickness might be more relevant to evaluate in power athletes with low LBM, while late RFD might be more relevant to evaluate in athletes with higher LBM.

Effects of low volume isometric leg press complex training at two knee angles on force-angle relationship and rate of force development

Abstract This study compared knee angle-specific neuromuscular adaptations after two low-volume isometric leg press complex training programmes performed at different muscle lengths. Fifteen young males were divided into two groups and trained three times per week for 6 weeks. One group (n = 8) performed 5–7 sets of 3 s maximum isometric leg press exercise, with 4 min recovery, with knee angle at 85° ± 2° (longer muscle-tendon unit length; L-MTU). The other group (n = 7) performed the same isometric training at a knee angle of 145° ± 2° (180° = full extension; shorter muscle-tendon unit length; S-MTU). During the recovery after each set of isometric exercise, participants performed two CMJ every minute, as a form of complex training. Maximum isometric force (MIF) and rate of force development (RFD) were measured over a wide range of knee angles. Countermovement jump (CMJ) performance and maximum half-squat strength (1RM) were also assessed. Training at S-MTU induced a large increase of MIF (22–58%, p < 0.02) and RFD (18–43%, p < 0.05 to 0.001) at knee angles close to the training angle and resulted in a 14° ± 9° shift of the force vs. knee joint angle relationship towards extended knee joint angles (p = 0.001). In contrast, training at L-MTU, resulted in a moderate and similar (≈12.3%, p = 0.028) improvement of force at all knee angles. CMJ performance and 1RM were equally increased in both groups after training by 10.4% ± 8.3% and 7.8% ± 4.7% (p < 0.001), respectively. Low-volume maximal isometric leg-press complex training at S-MTU causes angle-specific adaptations in isometric strength and RFD, while dynamic muscle performance is independent of muscle length during training.

Intramuscular fiber conduction velocity and muscle fascicle length in human vastus lateralis

Muscle fascicle length and muscle fibre conduction velocity (MFCV) are thought to be important parameters for power performance. It might be expected that faster muscle fibre conduction velocities would compensate for longer fascicle lengths to increase the speed of action potential propagation along the elongated fibres. However, the relationship between muscle fascicle length and MFCV remains unknown. The aim of the present study was to explore the relationship between average vastus lateralis MFCV and average fascicle length. In 17 moderately trained, healthy, male, physical education students (age, 23.4 ± 3.1 years; body height, 178 ± 5.5 cm; body mass, 82.7 ± 6.9 kg; body mass index, 24.6 ± 1.5 kg·m-2) resting MFCV was measured with intramuscular microelectrodes while muscle architecture was evaluated with ultrasonography. Fascicle length was highly correlated with total MFCV (r = 0.923, p = 0.000), maximum MFCV (r = 0.949, p = 0.000), and MFCV of the fastest (r = 0.709, p = 0.001), but not of the slowest fibres (r = 0.131, p = 0.616). No significant correlations were also found between vastus lateralis thickness or fascicle angle with any of MFCV parameters (r = 0.145-0.430; R2 < 0.130; p > 0.05). These data indicate that average MFCV is associated with average fascicle length in vastus lateralis muscle in different individuals. It seems that participants with longer fascicle lengths have also higher MFCVs.