Assessment of Muscle Contractile Properties at Acute Moderate Altitude Through Tensiomyography

Tensiomyography Allows to Discriminate between Injured and Non-Injured Biceps Femoris Muscle

The hamstring muscle group is the most frequently injured muscle group in non-contact muscle injuries in sports involving high-speed running. A total of 84% of hamstring injuries affect the biceps femoris (BF) muscle. Clinical assessments and magnetic resonance imaging (MRI) are routinely used for diagnosis and plan management. MRI-negative scans for clinically diagnosed hamstring injuries range from 14% to 45%. We tested the hypothesis that the functional differences between injured and non-injured BF assessed by tensiomyography can be used for diagnostic and classification purposes. We compared an injured group of 53 international-level soccer players and sprinters with 53 non-injured international-level soccer players and sprinters of both sexes. Comparing the injured vs. non-injured athletes and the left vs. right side in all of the athletes, we used the percentage of absolute differences in the BF contraction time (Tc) to classify non-injured and injured BF muscles. The receiver operating characteristic (ROC) curve and the area under the curve (AUC) and the precision−recall curve (PRC) were used to measure the classification accuracy and to identify cut-off limits using the Tc differences. There was a very high ROC AUC value of 0.981 (SE = 0.009, p < 0.000), with 98.11% of the injured muscles being correctly classified (cut-off point 12.50% on Tc differences), and an AUPRC value of 0.981, with association classification criteria at >9.87. Tensiomyography has a high predictive ability to discriminate between injured and non-injured BF non-invasively and functionally.

Muscle Contractile Properties Measured at Submaximal Electrical Amplitudes and Not at Supramaximal Amplitudes Are Associated with Repeated Sprint Performance and Fatigue Markers

Background: The present study analyzes the associations between the muscle contractile properties (MCP) measured at different neuromuscular electrical stimulation amplitudes (NMESa) and the performance or transient fatigue after a bout of repeated sprints. Methods: Seventeen physically active male subjects performed six repeated sprints of 30 m with 30 s of passive recovery. Capillary blood creatine kinase (CK) concentration, knee extension or flexion isometric peak torque, tensiomyography, and repeated sprint performance were assessed. Results: Muscle displacement and contraction time were different in relation to the NMESa used in the rectus femoris and biceps femoris muscles. At rest, significant (p < 0.05) associations were found between muscle displacement and the loss of time in the repeated sprints (sprint performance) at 20 or 40 mA in the rectus femoris. At post +24 h or +48 h, the highest significant associations were found between the muscle displacement or the contraction time and CK or peak torques also at submaximal amplitudes (20 mA). The NMESa which elicits the peak muscle displacement showed lack of practical significance. Conclusion: Although MCP are typically assessed in tensiomyography using the NMESa that elicit peak muscle displacement, a submaximal NMESa may have a higher potential practical application to assess neuromuscular fatigue in response to repeated sprints.

Acute Effects of Tissue Flossing Around the Upper Thigh on Neuromuscular Performance: A Study Using Different Degrees of Wrapping Pressure

CONTEXT

It has been recently demonstrated that tissue flossing around the ankle joint can be effectively used to improve ankle range of motion, jump, and sprint ability. However, there is a lack of studies investigating the acute effects of tissue flossing applied using different wrapping pressures.

OBJECTIVE

To investigate the acute effects of tissue flossing and the degree of floss band pressure, around the upper thigh on knee range of motion, strength, and muscle contractile characteristics.

DESIGN

Crossover design in 3 distinct sessions.

SETTING

University laboratory.

PARTICIPANTS

A total of 19 recreationally trained volunteers (age 23.8[4.8] y) participated in this study.

INTERVENTION

Active knee extension and flexion performed for 3 sets of 2 minutes (2-min rest between sets with wrapped upper thigh). Individualized wrapping pressures were applied to create conditions of high and moderate vascular occlusion, while a loose band application served as a control condition.

MAIN OUTCOME MEASURES

Participants were assessed for active straight leg raise test; tensiomyography displacement and contraction time for rectus femoris, vastus medialis, and biceps femoris muscles; and maximum voluntary contractions for knee extensors and flexors for pre, after, and 30 minutes after applying the floss band.

RESULTS

There was a statistically significant increase in maximum voluntary contractions for knee extensors and a significant shortening in rectus femoris contraction time for the moderate condition, which was associated with small to medium effects in favor of the moderate condition. There were no statistically significant changes observed between control and high conditions. The active straight leg raise test was unaffected regardless of intervention.

CONCLUSIONS

The results of this study suggest that tissue flossing around the upper thigh might have a localized as well as pressure-sensitive response, thereby improving neuromuscular function of the knee extensors.

Acute Effects of Tissue Flossing on Ankle Range of Motion and Tensiomyography Parameters

CONTEXT

Recently, a few papers have suggested that tissue flossing (TF) acutely improves range of motion (ROM) and neuromuscular performance. However, the effects of TF on muscle contractile properties are yet to be defined.

OBJECTIVE

To investigate the acute effects of TF on ankle ROM and associated muscle gastrocnemius medialis displacement and contraction time assessed with tensiomyography.

DESIGN

Crossover design in a single session.

SETTING

University laboratory.

PARTICIPANTS

Thirty recreationally trained volunteers (age 23.00 [4.51] y).

INTERVENTION

Active ankle plantar flexion and dorsiflexion were performed for the duration of 2 minutes (3 sets, 2-min rest between sets), while a randomly selected ankle was wrapped using TF elastic band (BAND) and the other ankle served as a control condition (CON).

MAIN OUTCOME MEASURES

Participants performed an active ankle plantar flexion and dorsiflexion ROM test and muscle gastrocnemius medialis tensiomyography displacement and contraction time measurement pre, 5, 15, 30, and 45 minutes after the floss band application.

RESULTS

There were no statistically significant differences between BAND and CON conditions (active ankle plantar flexion ROM: P = .09; active ankle dorsiflexion ROM: P = .85); however, all ROM measurements were associated with medium or large effect sizes in favor of BAND compared with CON. No significant changes were observed in the tensiomyography parameters.

CONCLUSIONS

The results of this study suggest that TF applied to the ankle is a valid method to increase ROM and at the same time maintaining muscular stiffness.

Assessment of fatigue-related biochemical alterations in a rat swimming model under hypoxia

It is well known that exercise-induced fatigue is exacerbated following hypoxia exposure and may arise from central and/or peripheral mechanisms. To assess the relative contribution of peripheral and central factors to exercise-induced fatigue under hypoxia, a rat model of fatigue by a bout of exhaustive swimming was established and fatigue-related biochemical changes in normoxic and severe hypoxic conditions were compared. Rats were randomly divided into four groups: normoxia resting (NR), exhaustive swimming (NE), hypoxia resting (HR) and exhaustive swimming (HE). The swimming time to exhaustion with a weight equal to 2.5% of their body weight reduced under hypoxia. There were lower blood lactate levels, lower gastrocnemius pAMPK/AMPK ratios and higher gastrocnemius glycogen contents in the HE than in the NE groups, which all suggested a lower degree of peripheral fatigue in the HE group than in the NE group. Meanwhile, there was a significant increase in striatal 3,4-dihydroxyphenylacetic acid (DOPAC) caused by exhaustive swimming under normoxia, whereas this increase was almost blunted under severe hypoxia, indicating that hypoxia might exacerbate exercise-induced central fatigue. These biochemical changes suggest that from normoxia to severe hypoxia, the relative contribution of peripheral and central factors to exercise-induced fatigue alters, and central fatigue may play a predominant role in the decline in exercise performance under hypoxia.

Effects of Recreational Ski Mountaineering on Cumulative Muscle Fatigue - A Longitudinal Trial

Sport is known to have many positive effects on mental and physical health. High-intensity exercise is considered to decrease muscle strength and induce muscle fatigue, which is associated with a higher risk of injury. In recreational alpine skiers, a decrease of eccentric peak hamstring torque, as an indication of muscle fatigue, occurs even after 1 day of skiing. The popularity of ski mountaineering is increasing enormously, but no studies are available on its effects on muscle strength. Therefore, the present study examined the consequences of ski mountaineering on muscle fatigue of the concentric/eccentric quadriceps and/or hamstrings. In addition, a possible role of myofascial foam rolling in reducing muscle fatigue was evaluated. Fifty recreational ski mountaineers (27 males, 23 females) completed five consecutive tours of ski mountaineering within 1 week. After each day of skiing, participants underwent an isokinetic muscle test assessing the concentric and eccentric muscle strength of both thighs. One group completed an additional session of myofascial foam rolling. Right and left concentric quadriceps peak torque, left hamstrings peak torque, left eccentric quadriceps peak torque, as well as right and left hamstring peak torque, were reduced after a single day of ski mountaineering (p ≤ 0.016 for all). However, no cumulative muscle fatigue was detected and we could not demonstrate any effect of myofascial foam rolling. The results show conclusively that a single day of ski mountaineering leads to a significant decrease of concentric and eccentric quadriceps and hamstring strength. Therefore, in order to improve muscle strength for the ski mountaineering season, a physical training program including concentric and eccentric methods can be recommended.