Can a human ever run 100m under nine seconds?

It is never easy to run 100m in less than ten seconds, as the recent Commonwealth Games demonstrated. However, as the world record stands at 9.58 seconds, the attention in recent years has turned to whether a human will be able to run 100m in less than nine seconds one day

EFFECTS OF ELECTRICAL MUSCLE STIMULATION ON MYOFASCIALS PAIN SYNDROME:A PRELIMINARY STUDY

Introduction: Many working adults suffer from upper back pain, especially in the trapezius muscle (TM). The myofascial trigger point (MTP) is formed by muscle overload, leading to cell ischemia and contributing to myofascial pain syndrome (MPS). MTPs cause discomfort and reduce muscle function. Current treatments reverse MTPs through com-bination therapy of passive stretching, and trigger point pressure release (TPR), which addresses the long-term effects [1]. However, electrical muscle stimulation (EMS) has the potential to show immediate effects on improving pain by facilitating greater stretch in the affected TM. This study aimed to evaluate the acute effects of EMS on MPS and compare changes in pain intensity (PI), pressure pain threshold (PPT) (both indicators of the MTP sensitivity), and EMG activity in response to different MPS treatments.Methods: Twelve healthy volunteers (4 males and 8 females; age 36.67 ± 12.02 years old), with an MTP in the TM were treated by 5 treatments (T1-T5) applied in a random order: (T1) passive stretching in the upper or middle TM sections, (T2) TPR, (T3) TPR combined with active TM stretching, (T4) active TM stretching with shoulder depression or scapular protraction combined with EMS, and (T5) a combination therapy of TPR and T4 (Fig. 1). The EMS consist-ed of a biphasic, stimulation frequency of 20 Hz with pulse width of 100 µs, and constant current amplitude adjusted for comfort level. The electrodes were applied at the opposite end of the MTP location to stimulate muscle contraction in the region. In doing so, this region would produce active resistance to the applied stretch, encouraging a greater stretch of the TM. The treatment was provided for 10s repeated 3 times with a 10s interval in between. After each treatment the participant rested for 2 minutes. sEMG recording of the MTP region of TM were taken during TM stretching and TM contraction (shoulder elevation or scapular retraction) to evaluate difference in magnitude and frequency of EMG. Differences in PI, PPT and EMG as a result of each treatment were evaluated using ANOVA. Results: Post T4, significant differences were observed in PI (t (11) = -4.022, p = .002) and PPT (t (11) = 4.492, p &lt; .001). Median frequency (MDF) significantly increased during TM action after treatments, but there was no difference amplitude (RMS) (Tab. 1). Combination therapy showed a significant decrease in RMS during TM stretching (F (4, 52) = 15.456, p &lt; .001).Discussion and conclusion: The results indicated that EMS applied during stretching has a significant acute effect on MPS, as evidenced by a reduction in pain (decreased PI and increased PPT) and an increase in EMG frequency during TM action which suggests improved muscle performance, and cell perfusion. Combination therapy showed promise in reducing MTP, which was possibly due to synergistic effects in optimizing muscle contraction which can break energy crisis [2]. However, it is important to note that the data was not segmented by TM sections, limiting the precision of the findings. Future investigations should consider sham stimulation and electrical nerve stimulation.<br/

EFFECTS OF ELECTRICAL MUSCLE STIMULATION ON MYOFASCIALS PAIN SYNDROME:A PRELIMINARY STUDY

Introduction: Many working adults suffer from upper back pain, especially in the trapezius muscle (TM). The myofascial trigger point (MTP) is formed by muscle overload, leading to cell ischemia and contributing to myofascial pain syndrome (MPS). MTPs cause discomfort and reduce muscle function. Current treatments reverse MTPs through com-bination therapy of passive stretching, and trigger point pressure release (TPR), which addresses the long-term effects [1]. However, electrical muscle stimulation (EMS) has the potential to show immediate effects on improving pain by facilitating greater stretch in the affected TM. This study aimed to evaluate the acute effects of EMS on MPS and compare changes in pain intensity (PI), pressure pain threshold (PPT) (both indicators of the MTP sensitivity), and EMG activity in response to different MPS treatments.Methods: Twelve healthy volunteers (4 males and 8 females; age 36.67 ± 12.02 years old), with an MTP in the TM were treated by 5 treatments (T1-T5) applied in a random order: (T1) passive stretching in the upper or middle TM sections, (T2) TPR, (T3) TPR combined with active TM stretching, (T4) active TM stretching with shoulder depression or scapular protraction combined with EMS, and (T5) a combination therapy of TPR and T4 (Fig. 1). The EMS consist-ed of a biphasic, stimulation frequency of 20 Hz with pulse width of 100 µs, and constant current amplitude adjusted for comfort level. The electrodes were applied at the opposite end of the MTP location to stimulate muscle contraction in the region. In doing so, this region would produce active resistance to the applied stretch, encouraging a greater stretch of the TM. The treatment was provided for 10s repeated 3 times with a 10s interval in between. After each treatment the participant rested for 2 minutes. sEMG recording of the MTP region of TM were taken during TM stretching and TM contraction (shoulder elevation or scapular retraction) to evaluate difference in magnitude and frequency of EMG. Differences in PI, PPT and EMG as a result of each treatment were evaluated using ANOVA. Results: Post T4, significant differences were observed in PI (t (11) = -4.022, p = .002) and PPT (t (11) = 4.492, p &lt; .001). Median frequency (MDF) significantly increased during TM action after treatments, but there was no difference amplitude (RMS) (Tab. 1). Combination therapy showed a significant decrease in RMS during TM stretching (F (4, 52) = 15.456, p &lt; .001).Discussion and conclusion: The results indicated that EMS applied during stretching has a significant acute effect on MPS, as evidenced by a reduction in pain (decreased PI and increased PPT) and an increase in EMG frequency during TM action which suggests improved muscle performance, and cell perfusion. Combination therapy showed promise in reducing MTP, which was possibly due to synergistic effects in optimizing muscle contraction which can break energy crisis [2]. However, it is important to note that the data was not segmented by TM sections, limiting the precision of the findings. Future investigations should consider sham stimulation and electrical nerve stimulation.<br/

The effect of foot orientation modifications on knee joint biomechanics during different activities

Introduction Foot position during daily activities can influence the magnitude and rate of knee joint loading [1]. Over time, increased loading can cause cumulative damage to the articulating surfaces of the knee joint, especially in people with existing knee osteoarthritis [2]. Knee joint loading is difficult to measure in vivo as the majority of knee loading is distributed on the medial compartment of the knee joint, therefore, knee adduction moment (KAM) is commonly used as a surrogate measure for knee joint loading [3].   Foot orientation is believed to have an impact on knee loading during daily activities such as walking and standing from a chair, altering the direction of the ground reaction force vector to reduce the adduction moment arm, relative to the knee joint [4]. However, limited studies have systematically explored the effect of foot orientation on KAM in activities other than walking, which is crucial for improving functional mobility and quality of life in this population beyond the lab. Therefore, this study aims to evaluate the effect of different foot orientations (toe-in, parallel and toe-out) on knee loading across several daily activities (walking, sit-to-stand, and stair climbing).   Methods Twenty-nine participants (56 ± 5 years, 170 ± 8 cm, 74 ± 14 kg) performed over-ground walking, stair climbing and sit-to-stand movements at their preferred constant speed under three foot conditions, 10° toe-in, 10° toe-out, neutral (0°). Participants performed walking and sit-to-stand on overground force plates, and stair climbing on a portable force plate embedded within the stairs. Each condition within each activity was repeated until five successful trials were obtained.   Three-dimensional kinematic (200 Hz) and kinetic data (1000 Hz) were recorded to obtain knee joint moments and foot progression angles. Foot progression angle was identified using the frontal angle of foot (defined as a 6DOF rigid body) to the global coordinate system (QTM). KAM was computed using inverse dynamics (Visual 3D) and normalised to body mass. Mean within-participant values were calculated for statistical analysis, with repeated measures ANOVA and Bonferroni post-hoc analysis used to compare the KAMs of three foot orientations across all activities.   Results KAMs during toe-in foot position were significantly lower than those under neutral foot position during walking (P = 0.011), stair climbing and sit-to-stand (P &lt; 0.001), while the KAMs during neutral foot position were significantly lower than those in toe-out foot position across all activities (P &lt; 0.001) (Fig 1). Figure 1: Median and interquartile, peak KAM for toe-out, toe-in and neutral foot position conditions during walking, stair climbing and sit-to-stand.   Discussion All results showed a significant decrease in peak KAM during the toe-in foot position condition compared to toe-out and neutral foot positions, which is consistent with previous gait studies. The results of this study indicate that toe-in gait can reduce knee joint loading not only during walking, but also in stair climbing and sit-to-stand activities.   The results of this study will be of help in gait retraining programme in clinics and rehabilitation aimed at minimising knee loading and joint pain to slow the progression of the disease. They may provide a range of clinical guidance for injury prevention in a healthy older population under the common contexts  of stair climbing and sit-to-stand, taking the technique outside the lab. Future studies should explore the effectiveness of altered foot orientation modifications on knee loading and pain reduction, in a patient population such as knee osteoarthritis.   References 1.   Valenzuela et al, J Sports Sci. Med, 15:50-56, 2016. 2.   Lynn et al, Clin Biomech, 23: 779-786, 2008. 3.   Manal et al, Osteoarthr. Cartil, 23:1107-1111, 2015. 4.   Rutherford et al, Osteoarthr. Cartil, 16:883-889, 2008.   Acknowledgements This project was funded by China Scholarship Council.</p

Backward Double Integration is a Valid Method to Calculate Maximal and Sub-Maximal Jump Height

The backward double integration method uses one force plate and could calculate jump height for countermovement jumping, squat jumping and drop jumping by analysing the landing phase instead of the push-off phase. This study compared the accuracy and variability of the forward double integration (FDI), backwards double integration (BDI) and Flight Time + Constant (FT+C) methods, against the marker-based rigid-body modelling method. It was hypothesised that the jump height calculated using the BDI method would be equivalent to the FDI method, while the FT+C method would have reduced accuracy and increased variability during sub-maximal jumping compared to maximal jumping. Twenty-four volunteers performed five maximal and five sub-maximal countermovement jumps, while force plate and motion capture data were collected. The BDI method calculated equivalent mean jump heights compared to the FDI method, with only slightly higher variability (2–3 mm), and therefore can be used in situations where FDI cannot be employed. The FT+C method was able to account for reduced heel-lift distance, despite employing an anthropometrically scaled heel-lift constant. However, across both sub-maximal and maximal jumping, it had increased variability (1.1 cm) compared to FDI and BDI and should not be used when alternate methods are available.</p

Can a human ever run 100m under nine seconds?

It is never easy to run 100m in less than ten seconds, as the recent Commonwealth Games demonstrated. However, as the world record stands at 9.58 seconds, the attention in recent years has turned to whether a human will be able to run 100m in less than nine seconds one day

Feasibility and acceptability of home-based exercise snacking and tai-chi snacking delivered remotely to self-isolating older adults during COVID-19.

The purpose of this study was to examine the feasibility and acceptability of remotely delivered, home-based exercise programs on physical function and well-being in self-isolating older adults during the COVID-19 pandemic. In a four-arm randomized controlled trial, 63 participants (aged 65 years and older) were allocated to one of three home-based daily (2 × 10-min) exercise interventions (exercise snacking, tai chi snacking, and combination) or control (UK National Health Service Web pages). Functional assessments were conducted via video call at baseline and 4-week follow-up. A web-based survey assessed the acceptability of each exercise program and secondary psychological/well-being outcomes. Ecological momentary assessment data, collected in Weeks 1 and 4, explored feeling states as antecedents and consequences of exercise. All intervention groups saw increased physical function at follow-up and displayed good adherence with exercise snacking considered the most acceptable program. Multilevel models revealed reciprocal associations between feelings of energy and exercise engagement. Further studies are needed with larger, more diverse demographic samples.</p

Horses Damp the Spring in Their Step

The muscular work of galloping in horses is halved by storing and returning elastic strain energy in spring-like muscle–tendon units1, 2.These make the legs act like a child\u27s pogo stick that is tuned to stretch and recoil at 2.5 strides per second. This mechanism is optimized by unique musculoskeletal adaptations: the digital flexor muscles have extremely short fibres and significant passive properties, whereas the tendons are very long and span several joints3, 4. Length change occurs by a stretching of the spring-like digital flexor tendons rather than through energetically expensive length changes in the muscle5. Despite being apparently redundant for such a mechanism5, the muscle fibres in the digital flexors are well developed. Here we show that the mechanical arrangement of the elastic leg permits it to vibrate at a higher frequency of 30–40 Hz that could cause fatigue damage to tendon and bone. Furthermore, we show that the digital flexor muscles have minimal ability to contribute to or regulate significantly the 2.5-Hz cycle of movement, but are ideally arranged to damp these high-frequency oscillations in the limb