Calculating lactate anaerobic thresholds in sports involving different endurance preparation

AbstractThe aim of this study was to establish the degree of similarity of exercise intensity values at the anaerobic threshold (AT) provided by five methods of lactate curve analysis, i.e., LTAT, LTloglog, 1 mmol AT, 4 mmol AT, and D-max. The pattern of similarities and differences was sought in athletes with varying levels of experience and sports skills, representing two disciplines with different prevailing types of power output during competition: on-road cycling (aerobic metabolism) and ice-hockey (anaerobic metabolism).All groups of athletes tested [Group 1: on-road cyclists (n = 19) at international sporting level (participants of the Olympic Games and World Championships); Group 2: on-road cyclists (n = 20) at national sporting level; Group 3: ice-hockey players (n = 24) at international sporting level (Polish National Team); and Group 4: ice-hockey players (n = 22) at international sporting level (Polish National Team U-20)] performed an incremental exercise.The greatest power values at the anaerobic threshold (PAT) were provided by the LTAT (221.93 ± 34.5 W) and 4 mmol AT (226.38 ± 32.33 W) methods, whereas the lowest were provided by the LTloglog (190.71 ± 25.92 W) method. The PAT produced by the LTloglog method was statistically significantly lower (p ≤ 0.001) than the values provided by LTAT, 4 mmol AT, and Dmax. The PAT levels were found to be statistically significantly different for power values determined using the 4 mmol AT and those produced by the 1 mmol AT (p ≤ 0.001) and D-max (p ≤ 0.01) methods. As shown by the analyses, PAT values vary in the international-level on-road cyclists depending on the method of lactate curve analysis applied

The influence of high-density lipoprotein cholesterol on maximal lipid core burden indexing thin cap fibrous atheroma lesions as assessed by near infrared spectroscopy

Background: Previous studies suggest that higher plasma concentrations of several lipid molecules are associated with higher lipid core burden index (LCBI) NIRS imaging. The aim of this study was to investigate whether an association between plasma lipids depends on plaque morphology (thin cap fibrous atheroma [TCFA] vs. non-TFCA) as measured by near-infrared spectroscopy–intravascular ultrasound (NIRS-IVUS). Methods: 64 patients retrospectively enrolled were diagnosed with stable coronary artery disease or acute coronary syndrome who underwent NIRS-IVUS imaging. Before percutaneous coronary intervention, blood samples were collected for measurement of serum levels of total cholesterol (TC), low-density lipoprotein cholesterol (HDL-C), high-density lipoprotein cholesterol (HDL-C) and triglycerides. Patients were divided into two groups based on maxLCBI4mm and IVUS imaging. Those with maxLCBI4mm ≥ 323 were included into TCFA group (n = 35) while others were assigned to the non-TCFA group (n = 29). Results: Thin cap fibrous atheroma (TCFA) lesions were significantly longer than the non-TCFA lesions (25.66 ± 9.56 vs. 17.03 ± 9.22, p = 0.001). TCFA characterizes greater plaque burden (78.4 [70.9, 82.2] vs. 72.70 [64.77, 76,05]; p = 0.021) and plaque volume (176.1 [110.75, 247.5] vs. 68.1 [55.58, 143.35]; p = 0.000) as compared to non-TCFA. In TCFA suspected lesions, there was no correlation between maxLCBI4mm and LDL levels (r = 0.105, p = 0.549) nor TC levels (r = –0.035, p = 0.844) but a negative correlation was found between HDL-C and maxLCBI4mm (r = –0.453, p = 0.007). Conclusions: The present study showed that there was no correlation between plasma LDL-C, TCH and TG level and the amount of lipids in coronary plaque assessed by NIRS in both TCFA and non-TCFA groups. Only HDL-C correlated with maxLCBI4mm in TCFA lesions

Coronary plaque redistribution after stent implantation is determined by lipid composition: A NIRS-IVUS analysis

Background: The composition of plaque impacts the results of stenting. The following study evaluated plaque redistribution related to stent implantation using combined near-infrared spectroscopy and intravascular ultrasound (NIRS-IVUS) imaging. Methods: The present study included 49 patients (mean age 66 ± 11 years, 75% males) presenting with non-ST elevation myocardial infarction (8%), unstable angina (49%) and stable coronary artery disease (43%). The following parameters were analyzed: mean plaque volume (MPV, mm3), plaque burden (PB, %), remodeling index (RI), and maximal lipid core burden index in a 4 mm segment (maxLCBI4mm). High-lipid burden lesions (HLB) were defined as by maxLCBI4mm > 265 with positive RI. Otherwise plaques were defined as low-lipid burden lesions (LLB). Measurements were done in the target lesion and in 4 mm edges of the stent before and after stent implantation. Results: MPV and maxLCBI4mm decreased in both HLB (MPV 144.70 [80.47, 274.25] vs. 97.60 [56.82, 223.45]; maxLCBI4mm: 564.11 ± 166.82 vs. 258.11 ± 234.24, p = 0.004) and LLB (MPV: 124.50 [68.00, 186.20] vs. 101.10 [67.87, 165.95]; maxLCBI4mm: 339.07 ± 268.22 vs. 124.60 ± 160.96, p < 0.001), but MPV decrease was greater in HLB (28.00 [22.60, 57.10] vs. 13.50 [1.50, 28.84], p = 0.019). Only at the proximal stent edge of LLB, maxLCBI4mm decreased (34 [0, 207] vs. 0 [0, 45], p = 0.049) and plaque burden increased (45.48 [40.34, 51.55] vs. 51.75 [47.48, 55.76], p = 0.030). Conclusions: NIRS-IVUS defined HLB characterized more significant decreases in plaque volume by stenting. Plaque redistribution to the proximal edge of the implanted stent occurred only in LLB

The Effects of a Combined Pre- and Post-Operative Anterior Cruciate Ligament Reconstruction Rehabilitation Program on Lower Extremity Muscle Imbalance

This study examined whether the 5-week pre-operative progressive exercise rehabilitation program with weekly monitoring contributed to a significantly lower muscle activity imbalance in the treatment group, both before and immediately after anterior cruciate ligament reconstruction (ACLR), as well as during the next 5 weeks in comparison to the control group. Twelve professional soccer players took part in the study (from among the top three Polish levels of competition) (age: 26 ± 5 years, body mass: 73 ± 7 kg, stature: 180 ± 6 cm, training experience: 15 ± 4 years). The participants were randomly assigned to the treatment group (n = 6) or to the control group (n = 6). Both groups performed the same pre- and post-operative progressive exercise rehabilitation program, while the rehabilitation of the treatment group was extended by supplementary body-weight functional stabilization training. The three-way repeated-measures ANOVA revealed a statistically significant interaction for muscle × group × time (p 2 = 0.806). The post-hoc analysis for the interaction effect of muscle × group × time indicated a significantly higher muscle activity imbalance for every measured muscle in the control group at any time point than in the treatment group (from p = 0.036 to p p p p < 0.001). The results of this study showed that the 5-week pre-operative rehabilitation program with weekly monitoring influenced outcomes of the post-operative phase. Nevertheless, performing both pre- and post-ACLR rehabilitation significantly reduced the muscle activity imbalance of lower limbs, but in the case of the quadriceps muscles, not to a sufficient level

The Effects of a Combined Pre- and Post-Operative Anterior Cruciate Ligament Reconstruction Rehabilitation Program on Lower Extremity Muscle Imbalance

This study examined whether the 5-week pre-operative progressive exercise rehabilitation program with weekly monitoring contributed to a significantly lower muscle activity imbalance in the treatment group, both before and immediately after anterior cruciate ligament reconstruction (ACLR), as well as during the next 5 weeks in comparison to the control group. Twelve professional soccer players took part in the study (from among the top three Polish levels of competition) (age: 26 &plusmn; 5 years, body mass: 73 &plusmn; 7 kg, stature: 180 &plusmn; 6 cm, training experience: 15 &plusmn; 4 years). The participants were randomly assigned to the treatment group (n = 6) or to the control group (n = 6). Both groups performed the same pre- and post-operative progressive exercise rehabilitation program, while the rehabilitation of the treatment group was extended by supplementary body-weight functional stabilization training. The three-way repeated-measures ANOVA revealed a statistically significant interaction for muscle &times; group &times; time (p &lt; 0.0001; F = 24.897; &eta;2 = 0.806). The post-hoc analysis for the interaction effect of muscle &times; group &times; time indicated a significantly higher muscle activity imbalance for every measured muscle in the control group at any time point than in the treatment group (from p = 0.036 to p &lt; 0.0001). The muscle activity imbalance was significantly higher from the 1st to 4th weeks than in the last week before surgery for quadriceps (p &lt; 0.016 for all) and hamstrings (p &lt; 0.001). However, in the case of gluteal muscles&rsquo; activity imbalance, it was significantly higher at every time point of the post-operative phase than in the last week before surgery (p &lt; 0.001). The results of this study showed that the 5-week pre-operative rehabilitation program with weekly monitoring influenced outcomes of the post-operative phase. Nevertheless, performing both pre- and post-ACLR rehabilitation significantly reduced the muscle activity imbalance of lower limbs, but in the case of the quadriceps muscles, not to a sufficient level

Evaluation of Lower Limb Muscle Electromyographic Activity during 400 m Indoor Sprinting among Elite Female Athletes: A Cross-Sectional Study

The purpose of this cross-sectional study was to analyze changes in normalized surface electromyography (sEMG) signals for the gastrocnemius medialis, biceps femoris, gluteus maximus, tibialis anterior, and vastus lateralis muscles occurring during a 400 m indoor sprint between subsequent curved sections of the track. Ten well-trained female sprinters (age: 21 &plusmn; 4 years; body mass: 47 &plusmn; 5 kg; body height: 161 &plusmn; 7 cm; 400 m personal best: 52.4 &plusmn; 1.1 s) performed an all-out 400 m indoor sprint. Normalized sEMG signals were recorded bilaterally from the selected lower limb muscles. The two-way ANOVA (curve &times; side) revealed no statistically significant interaction. However, the main effect analysis showed that normalized sEMG signals significantly increased in subsequent curves run for all the studied muscles: gastrocnemius medialis (p = 0.003), biceps femoris (p &lt; 0.0001), gluteus maximus (p = 0.044), tibialis anterior (p = 0.001), and vastus lateralis (p = 0.023), but differences between limbs were significant only for the gastrocnemius medialis (p = 0.012). The results suggest that the normalized sEMG signals for the lower limb muscles increased in successive curves during the 400 m indoor sprint. Moreover, the gastrocnemius medialis of the inner leg is highly activated while running curves; therefore, it should be properly prepared for high demands, and attention should be paid to the possibility of the occurrence of a negative adaptation, such as asymmetries

Changes in Muscle Activity Imbalance of the Lower Limbs Following 3 Weeks of Supplementary Body-Weight Unilateral Training

This study examined the effects of a short-term supplementary body-weight training program on changes in the muscle activity imbalance of the lower limbs during high-speed running in soccer players. Fifteen professional male soccer players took part in the study (age: 25 ± 5 years, body mass: 79.2 ± 10.8 kg, stature: 177 ± 10 cm, training experience: 12 ± 5 years). The evaluations of lower limb muscle activity imbalance via surface electromyography (sEMG) were performed twice (pre- and post-intervention), at a three-week interval. The sEMG was measured bilaterally from the area of quadriceps (Q), hamstrings (H), and gluteal muscles (G) during high-speed running at 18 km/h using sEMG shorts. Between measurements, the athletes performed the supplementary body-weight program of the lower limbs 4 times a week for 3 weeks. The training included six body-weight exercises performed unilaterally. The load progression included an additional set of each exercise in successive weeks of the experiment. The two-way repeated-measures ANOVA indicated a statistically significant main interaction for time × muscle (p = 0.006; F = 6.948; η2 = 0.332). The post-hoc analysis for the interaction effect of time × muscle showed a statistically significant decrease in muscle imbalance for the post-intervention compared to the pre-intervention for the H (p p = 0.002; ES = 0.92), and T (p p = 0.56; ES = 0.14). Moreover, there was a statistically significant greater imbalance between the H, G, and T muscles versus Q (p = 0.043, ES = 1.15; p = 0.006, ES = 1.57; p = 0.001, ES = 1.69, respectively) for the values recorded pre-intervention. Changes in muscle activity after 3 weeks of sports-specific movement patterns were statistically significant. For the gluteal (G) and hamstring (H), the imbalance between the limbs decreased significantly (p = 0.01). The imbalance in the quadriceps muscles (Q), with respect to each limb, did not decrease significantly (p = 0.82) following the training intervention. Conclusions: The results of this study indicate that in-season soccer training supplemented with a body-weight training program successfully decreases gluteal and hamstring imbalance between limbs after 3 weeks of training

Changes in Muscle Activity Imbalance of the Lower Limbs Following 3 Weeks of Supplementary Body-Weight Unilateral Training

This study examined the effects of a short-term supplementary body-weight training program on changes in the muscle activity imbalance of the lower limbs during high-speed running in soccer players. Fifteen professional male soccer players took part in the study (age: 25 ± 5 years, body mass: 79.2 ± 10.8 kg, stature: 177 ± 10 cm, training experience: 12 ± 5 years). The evaluations of lower limb muscle activity imbalance via surface electromyography (sEMG) were performed twice (pre- and post-intervention), at a three-week interval. The sEMG was measured bilaterally from the area of quadriceps (Q), hamstrings (H), and gluteal muscles (G) during high-speed running at 18 km/h using sEMG shorts. Between measurements, the athletes performed the supplementary body-weight program of the lower limbs 4 times a week for 3 weeks. The training included six body-weight exercises performed unilaterally. The load progression included an additional set of each exercise in successive weeks of the experiment. The two-way repeated-measures ANOVA indicated a statistically significant main interaction for time × muscle (p = 0.006; F = 6.948; η2 = 0.332). The post-hoc analysis for the interaction effect of time × muscle showed a statistically significant decrease in muscle imbalance for the post-intervention compared to the pre-intervention for the H (p &lt; 0.001; ES = 1.32), G (p = 0.002; ES = 0.92), and T (p &lt; 0.001; ES = 1.54), but not for Q (p = 0.56; ES = 0.14). Moreover, there was a statistically significant greater imbalance between the H, G, and T muscles versus Q (p = 0.043, ES = 1.15; p = 0.006, ES = 1.57; p = 0.001, ES = 1.69, respectively) for the values recorded pre-intervention. Changes in muscle activity after 3 weeks of sports-specific movement patterns were statistically significant. For the gluteal (G) and hamstring (H), the imbalance between the limbs decreased significantly (p = 0.01). The imbalance in the quadriceps muscles (Q), with respect to each limb, did not decrease significantly (p = 0.82) following the training intervention. Conclusions: The results of this study indicate that in-season soccer training supplemented with a body-weight training program successfully decreases gluteal and hamstring imbalance between limbs after 3 weeks of training

A systematic review of surface electromyography analyses of the bench press movement task

<div><p>Background</p><p>The bench press exercise (BP) plays an important role in recreational and professional training, in which muscle activity is an important multifactorial phenomenon. The objective of this paper is to systematically review electromyography (EMG) studies performed on the barbell BP exercise to answer the following research questions: Which muscles show the greatest activity during the flat BP? Which changes in muscle activity are related to specific conditions under which the BP movement is performed?</p><p>Strategy</p><p>PubMed, Scopus, Web of Science and Cochrane Central Register of Controlled Trials (CENTRAL) in the Cochrane Library were searched through June 10, 2016. A combination of the following search terms was used: bench press, chest press, board press, test, measure, assessment, dynamometer, kinematics and biomechanics. Only original, full-text articles were considered.</p><p>Results</p><p>The search process resulted in 14 relevant studies that were included in the discussion. The triceps brachii (TB) and pectoralis major (PM) muscles were found to have similar activity during the BP, which was significantly higher than the activity of the anterior deltoid. During the BP movement, muscle activity changes with exercise intensity, velocity of movement, fatigue, mental focus, movement phase and stability conditions, such as bar vibration or unstable surfaces. Under these circumstances, TB is the most common object of activity change.</p><p>Conclusions</p><p>PM and TB EMG activity is more dominant and shows greater EMG amplitude than anterior deltoid during the BP. There are six factors that can influence muscle activity during the BP; however, the most important factor is exercise intensity, which interacts with all other factors. The research on muscle activity in the BP has several unresolved areas, such as clearly and strongly defined guidelines to perform EMG measurements (e.g., how to elaborate with surface EMG limits) or guidelines for the use of exact muscle models.</p></div