Effects of lower and upper body fatigue in striking response time of amateur karate athletes

In combat sports, strikes or counter-strikes response time (RT) can be related to performance and sporting success. Moreover, training sessions are usually highly fatiguing, which is expected to impair basic skills, such as RT. Thus, this study aimed to investigate the effect of fatigue on punch and kick RTs of karate practitioners. Twelve individuals of both sexes from different levels (three yellow belts, three red belts, two orange belts, two green belts, one brown belt, and one black belt) were selected. Participants were aged 22 ± 3 years old, with a stature of 169.1 ± 6.5 cm, and a body mass of 65.5 ± 10 kg. Six visits were held with each participant. On the first 2 days, the RT of punches and kicks was measured by a validated smartphone app (TReaction). For the subsequent visits, a randomized incremental test for the upper or lower body was adopted as motor fatigue protocol, immediately followed by punches and kicks RT tests, also in random order. For induction of lower and upper body-specific muscle fatigue, the ITStriker app was used, which operates by emitting sound signals transmitted by a smartphone. One-way repeated measures ANOVA was performed, and significance was set at p ≤ 0.05. Regarding the mean punches RT, significant effects between situations for the upper (F_(2,22) = 11.5; ω² = 0.23; p < 0.001) and lower body (F_(2,22) = 14.2; ω² = 0.18; p < 0.001) fatigue protocols were found. The negative effect of the lower body fatigue protocol in punches RT was evident regardless of the order of the tests (punch RT first: Δ = 10.5%; t = 4.4; p < 0.001; d = 1.0; kick RT first: Δ = 11.4%; t = 4.8; p < 0.001; d = 1.1). Regarding mean kicks RT, significant effects were found between situations for the lower (F_(2,22) = 16.6; ω² = 0.27; p < 0.001) but not for the upper (F_(2,22) = 2.3; ω² = 0.02; p = 0.12) body fatigue protocols. Kick RTs were negatively affected by the lower body fatigue protocol regardless of the RT order applied (punch RT first: Δ = 7.5%; t = 3.0; p = 0.01; d = 0.8; kick RT first: Δ = 14.3%; t = 5.7; p < 0.001; d = 1.5). Upper body fatigue does not impair punch or kick RTs. Thus, it is concluded that the specificity of fatigue protocols and striking order should be considered while performing RT demanding techniques in karate practice. Specifically, lower body motor fatigue may impair both kicks and punches RT, which highlights the role of lower limbs in punches performance. Otherwise, upper body motor fatigue seems to induce impairments that are limited to the specific motor actions of this body segment.

Energy demands in high-intensity intermittent taekwondo specific exercises

Background

Taekwondo is an intermittent Olympic combat sport, which shows an aerobic predominance in matches and high participation of alactic metabolism for actions that determine competitive success. However, there is no information on energetic contribution systems in different high-intensity intermittent exercises for metabolic conditioning with specific movements. The study aimed to measure the physiological demands, mainly the energy expenditure, in taekwondo-specific high-intensity intermittent exercises (HIIE).

Methods

This study recruited ten male black belt athletes with a mean age of 20.2 ± 4 years, body mass of 62.8 ± 10.5 kg and height of 170.6 ± 7.8 cm, and total practice time of 11.8 ± 5.4 years. Subjects performed an incremental specific test and three different HIIE protocols on nonconsecutive days, and all comprised three 2-min rounds and 1 min of recovery between rounds. Heart rate, oxygen consumption, and blood lactate were measured. Energetic expenditure of aerobic, alactic, and lactic metabolisms was estimated through oxygen consumption, excess post-exercise oxygen consumption, and peak blood lactate after each round.

Results

For the mean of the three rounds, the TKDtest100 resulted in higher absolute and relative contribution from the aerobic metabolism (52.4 ± 4%; p = 0.01) and lower than the 35:5 relative alactic contribution (48.7 ± 5.4%; p = 0.03).

Conclusion

The mean of the three rounds for 35:5 and 15:10:5 presented similar absolute and relative contributions of aerobic and alactic metabolisms, whereas the TKDtest100 was a predominantly aerobic activity. We emphasize that aerobic metabolism was predominant from the second round in the 15:10:5 and 100%TKDtest protocols and in the last round of the 35:5 protocol.

High and Low-speed Resistance Training Induce Similar Physical and Functional Responses in Older Women

This study aimed to compare the effects of high-speed resistance training (HSRT) and low-speed resistance training (LSRT) in physical fitness, and functional performance in untrained older women. Twenty-four women (62.2 ± 2.7 years old) were allocated to the HSRT or LSRT groups. The HSRT and LSRT groups underwent a similar training program [3 sets of 8 to 12 repetitions at 90% of 10 maximum repetitions] for 14 weeks, twice a week. The LSRT group performed the exercises with 3 seconds in the concentric and eccentric phases, while the HSRT group performed with the concentric phase as quickly as possible and 3 seconds in the eccentric phase. Participants completed pre-and post-training testing to assess strength, flexibility, muscle endurance, power, walking speed, functional balance, and aerobic endurance. Two-way mixed-model ANOVA with repeated measures was applied for each variable, and the Bonferroni post hoc was used when necessary. Statistical significance was set at p < 0.05. No significant group*time interactions were found for any variable. Time main-effect suggested significant improvements for the 10 RM bench press (F = 46.1; p < 0.001), 10 RM leg press (F = 49.8; p < 0.001), sit-to-stand test (F = 10.4; p = 0.004), sit and reach (F = 10.5; p = 0.004), Timed Up-and-Go (F = 29.8; p < 0.001) and 6-min walking test (F = 41.6; p < 0.001). Thus, the configurations of RT tested here were similarly efficient to improve the functional performance of untrained older women. In addition, both groups showed significant gains in muscle strength, but not in muscle power and gait speed.

Physiological aspects and energetic contribution in 20s:10s high-intensity interval exercise at different intensities

Background

One of the most popular high-intensity interval exercises is the called “Tabata Protocol”. However, most investigations have limitations in describing the work intensity, and this fact appears to be due to the protocol unfeasibility. Furthermore, the physiological demands and energetic contribution during this kind of exercise remain unclear.

Methods

Eight physically active students (21.8 ± 3.7 years) and eight well-trained cycling athletes (27.8 ± 6.4 years) were enrolled. In the first visit, we collected descriptive data and the peak power output (PPO). On the next three visits, in random order, participants performed interval training with the same time structure (effort:rest 20s:10s) but using different intensities (115%, 130%, and 170% of PPO). We collected the number of sprints, power output, oxygen consumption, blood lactate, and heart rate.

Results

The analysis of variance for multivariate test (number of sprints, power output, blood lactate, peak heart rate and percentage of maximal heart rate) showed significant differences between groups (F = 9.62; p = 0.001) and intensities (F = 384.05; p < 0.001), with no interactions (F = 0.94; p = 0.57). All three energetic contributions and intensities were different between protocols. The higher contribution was aerobic, followed by alactic and lactic. The aerobic contribution was higher at 115%PPO, while the alactic system showed higher contribution at 130%PPO. In conclusion, the aerobic system was predominant in the three exercise protocols, and we observed a higher contribution at lower intensities.

Physical fitness predicts technical-tactical and time-motion profile in simulated Judo and Brazilian Jiu-Jitsu matches

Background

Among combat sports, Judo and Brazilian Jiu-Jitsu (BJJ) present elevated physical fitness demands from the high-intensity intermittent efforts. However, information regarding how metabolic and neuromuscular physical fitness is associated with technical-tactical performance in Judo and BJJ fights is not available. This study aimed to relate indicators of physical fitness with combat performance variables in Judo and BJJ.

Methods

The sample consisted of Judo (n = 16) and BJJ (n = 24) male athletes. At the first meeting, the physical tests were applied and, in the second, simulated fights were performed for later notational analysis.

Results

The main findings indicate: (i) high reproducibility of the proposed instrument and protocol used for notational analysis in a mobile device; (ii) differences in the technical-tactical and time-motion patterns between modalities; (iii) performance-related variables are different in Judo and BJJ; and (iv) regression models based on metabolic fitness variables may account for up to 53% of the variances in technical-tactical and/or time-motion variables in Judo and up to 31% in BJJ, whereas neuromuscular fitness models can reach values up to 44 and 73% of prediction in Judo and BJJ, respectively. When all components are combined, they can explain up to 90% of high intensity actions in Judo.

Discussion

In conclusion, performance prediction models in simulated combat indicate that anaerobic, aerobic and neuromuscular fitness variables contribute to explain time-motion variables associated with high intensity and technical-tactical variables in Judo and BJJ fights.

Defining the number of bouts and oxygen uptake during the "Tabata protocol" performed at different intensities

It is usually reported that the Tabata protocol (TP) is performed with eight bouts of 20:10 intervals at a load equivalent to 170% of i V̇ O₂max. However, the feasibility of accumulating 160 s of work at 170% i V̇ O₂max has been questioned. This article tested the intensity that would allow the performance of the original TP on a cycle ergometer, and measured the highest value of oxygen consumption (V̇ O₂) obtained during the TP and the time spent above 90% of the maximal oxygen uptake (V̇ O₂max) during the TP performed at different intensities. Thirteen young active males (25.9 ± 5.5 years, 67.9 ± 9.2 kg, 1.70 ± 0.06 m, 23.6 ± 3.1 kg·m^-2) participated in the study. Participants performed a graded exertion test (GXT) on a cycle ergometer to obtain maximum oxygen consumption (V̇ O₂max) and the intensity associated with V̇ O₂max (i V̇ O₂max). V̇ O₂, maximal heart rate (HRmax), and number of bouts performed were evaluated during the TP performed at 115%, 130%, and 170% of i V̇ O₂max. V̇ O₂max, HRmax, and iV̇ O₂max were 51.8 ± 8.0 mL.kg^-1·min^-1, 186 ± 10 bpm, and 204 ± 26 W, respectively. The number of bouts performed at 115% (7 ± 1 bouts) was higher than at 130% (5 ± 1 bouts) and 170% (4 ± 1 bouts) (p < .0001). The highest V̇ O₂ achieved at 115%, 130%, and 170% of iV̇ O₂max was 54.2 ± 7.9 mL·kg^-1·min^-1, 52.5 ± 8.1 mL·kg^-1·min^-1, and 49.6 ± 7.5 mL·kg^-1·min^-1, respectively. Non significant difference was found between the highest V̇ O₂ achieved at different intensities, however qualitative magnitude-inference indicate a likely small effect between 115% and 170% of iV̇ O₂max. Time spent above 90% of the V̇ O₂max during the TP at 115% (50 ± 48 s) was higher than 170% (23 ± 21 s; p < 0.044) with a probably small effect. In conclusion, our data suggest that the adequate intensity to perform a similar number of bouts in the original TP is lower than previously proposed, and equivalent to 115% of the iV̇ O₂max. In addition, intensities between 115 and 130% of the iV̇ O₂max should be used to raise the time spent above 90% V̇O₂max.

Time-Motion and Biological Responses in Simulated Mixed Martial Arts Sparring Matches

Coswig, VS, Ramos, SdP, and Del Vecchio, FB. Time-motion and biological responses in simulated mixed martial arts sparring matches. J Strength Cond Res 30(8): 2156-2163, 2016-Simulated matches are a relevant component of training for mixed martial arts (MMA) athletes. This study aimed to characterize time-motion responses and investigate physiological stress and neuromuscular changes related to MMA sparring matches. Thirteen athletes with an average age of 25 ± 5 years, body mass of 81.3 ± 9.5 kg, height of 176.2 ± 5.5 cm, and time of practice in MMA of 39 ± 25 months participated in the study. The fighters executed three 5-minute rounds with 1-minute intervals. Blood and salivary samples were collected and physical tests and psychometric questionnaires administered at 3 time points: before (PRE), immediately after (POST), and 48 hours after the combat (48 h). Statistical analysis applied analysis of variance for repeated measurements. In biochemical analysis, significant changes (p ≤ 0.05) were identified between PRE and POST (glucose: 80.3 ± 12.7 to 156.5 ± 19.1 mg·ml; lactate: 4 ± 1.7 to 15.6 ± 4.8 mmol·dl), POST and 48 hours (glucose: 156.5 ± 19.1 to 87.6 ± 15.5 mg·ml; lactate: 15.6 ± 4.8 to 2.9 ± 3.5 mmol·dl; urea: 44.1 ± 8.9 to 36.3 ± 7.8 mg·ml), and PRE and 48 hours (creatine kinase [CK]: 255.8 ± 137.4 to 395.9 ± 188.7 U/L). In addition, time-motion analyses showed a total high:low intensity of 1:2 and an effort:pause ratio of 1:3. In conclusion, simulated MMA sparring matches feature moderate to high intensity and a low degree of musculoskeletal damage, which can be seen by absence of physical performance and decrease in CK. Results of the study indicate that sparring training could be introduced into competitive microcycles to improve technical and tactical aspects of MMA matches, due to the high motor specificity and low muscle damage.

Kinematics and Kinetics of Multiple Sets Using Lifting Straps During Deadlift Training

The deadlift is a fundamental exercise used in the development of whole body strength and a common element in resistance training programs for all levels. However, many practitioners report the fatigue of forearm muscles and possibly a lack of grip strength as obstacles to exercise performance, which may lead to the use of ergogenic aids, such as lifting straps. The objective of this study was to evaluate kinematic variables during the execution of multiple sets of deadlift with (WS) and without (NS) lifting straps. Eleven subjects (25 ± 3.3 years) with an average of 4 ± 2.6 years of resistance training experience were enrolled in the study. After the 1 repetition maximum (1RM) test WS and NS, subjects performed separate trials of 3 sets to failure at 90% of 1RM in a counterbalanced fashion. With straps resulted in lower speed (0 to -25%) (-3 to -10%) and greater force (20-28%) and duration (concentric phase: 0-13%) when compared with NS. Therefore, it is concluded that the use of straps directly influences exercise performance that requires manual grip strength, increasing the amount of work performed by the target muscles.