| 1. |
|
|
| 2. |
|
|
| 3. |
|
|
| 4. |
- Halder, Amitava, et al.
(author)
-
Effects of Cooling on Ankle Muscle Strength, Electromyography, and Gait Ground Reaction Forces
- 2014
-
In: Journal of Sports Medicine. - : Hindawi Limited. - 2314-6176 .- 2356-7651. ; 2014
-
Journal article (peer-reviewed)abstract
- The effects of cooling on neuromuscular function and performance during gait are not fully examined. The purpose of this study was to investigate the effects of local cooling for 20 min in cold water at 10 C in a climate chamber also at 10 C on maximal isometric force and electromyographic (EMG) activity of the lower leg muscles. Gait ground reaction forces (GRFs) were also assessed. Sixteen healthy university students participated in the within subject design experimental study. Isometric forces of the tibialis anterior (TA) and the gastrocnemius medialis (GM) were measured using a handheld dynamometer and the EMG was recorded using surface electrodes. Ground reaction forces during gait and the required coefficient of friction (RCOF) were recorded using a force plate. There was a significantly reduced isometric maximum force in the TA muscle (
|
|
| 5. |
- Halder, Amitava, et al.
(author)
-
Effects of cooling on muscle function and duration of stance phase during gait
- 2015
-
In: Extreme Physiology & Medicine. - : Springer Science and Business Media LLC. - 2046-7648.
-
Conference paper (peer-reviewed)abstract
- Introduction: Cold exposure alters muscular function. Muscle cooling influences the neuromuscular activation during maximal isometric voluntary contractions (MVC) and the amplitude of surface electromyography (sEMG) [1],[2]. It also slows down the mechanical process during contraction [3]. The purpose of this study was to investigate the effects of local cooling in cold water at 10 °C for 20 min in a climate chamber on lower leg muscle activity and gait pattern. Methods: Sixteen healthy adults (eight females), aged Mean (SD) 27.0(2.9) years; body mass 66.3(9.8) kg; and height 169.5(7.8) cm participated in this experimental study. The median frequency (MF) and mean power frequency (MPF) of sEMG from tibialis anterior (TA) and gastrocnemius medialis (GM) muscles during MVC in ankle planter (PF) and dorsi-flexion (DF) against a hand-held dynamometer as well as contact times on a force plate during gait before and after cooling were measured and analysed. Results: The MF and MPF were significantly lower (P<0.01*) in both TA and GM muscle during MVC and in TA during gait trials after cooling. However, the frequency analysis for GM muscle showed no significant difference (P=0.46 and 0.06, respectively) either in MF or MPF during walking on level surface (table 1). Table 1: The means and SD (Hz) for the MF and MPF of the TA and GM during gait and MVC trials before and after cooling (N=16). sEMG Tibialis Anterior (TA) Gastrocnemius Medialis GM Pre Cooling Post Cooling Pre Cooling Post Cooling Gait MF 83.0±10.2* 69.9±9.6* 81.6±12.6 79.3±11.1 Gait MPF 99.7±11.5* 82.3±11.7* 99.8±13.2 93.2±12.4 MVC MF 87.0±9.7* 50.0±6.1* 111.7±16.7* 90.8±14.8* MVC MPF 100.7±10.6* 59.8±7.7* 129.1±15.3* 101.0±16.1* Fig 1: Duration of stance phase in gait trials. Additionally, the post cooling stance phase over the force plate was significantly (P= 0.013) longer than pre-cooling. Discussion: The significant time difference might be caused by the cold induced MF and MPF decrease in sEMG. Our previous investigation reported that cooling increased the sEMG amplitude and produced fatigue like responses in the leg muscles [2]. Moreover, other studies showed that muscle fatigue resulted in electromechanical delay during cold exposure [1], [4]. Conclusion: Moderate degree and duration of cooling may affect muscle motor unit firing rates, thus shifting the sEMG spectrum to lower frequencies, therefore decreasing the leg muscle force production. The result suggests that muscle cooling can cause cold induced frequency decrease in sEMG similar to fatigue response and lead to reduced muscle performance. References: 1. Cè, E., Rampichini, S., Agnello, L., Limonta, E., Veicsteinas, A., & Esposito, F. (2013). Effects of temperature and fatigue on the electromechanical delay components. Muscle & Nerve, 47(4), 566-576. doi:10.1002/mus.23627. 2. Halder A, Gao C, Miller M. (2014). Effects of cooling on ankle muscle maximum performances, gait ground reaction forces and electromyography. Journal of Sports Medicine.doi:10.1155/2014/520124. 3. Drinkwater, E. (2008). Effects of peripheral cooling on characteristics of local muscle. Medicine and Sport Science, 5374-88. doi:10.1159/000151551. 4. Rampichini, S., Cè, E., Limonta, E., & Esposito, F. (2014). Effects of fatigue on the electromechanical delay components in gastrocnemius medialis muscle. European Journal of Applied Physiology, 114(3), 639-651. doi:10.1007/s00421-013-2790-9.
|
|
| 6. |
|
|
| 7. |
- Halder, Amitava, et al.
(author)
-
Effects of leg fatigue due to exhaustive stair climbing on gait biomechanics while walking up a 10˚ incline – implications for evacuation and work safety
- 2021
-
In: Fire Safety Journal. - : Elsevier BV. - 0379-7112.
-
Journal article (peer-reviewed)abstract
- This biomechanics study explored stride length (SL), duration (SDN), and gait ground reaction forces (GRFspeak), required coefficient of friction (RCOFpeak), joint angle (anglepeak, anglemin), angular velocities (angvelx peak), angular accelerations (angaccx peak), muscle electromyography (EMG) during the dominant leg stance phase (SP) following an exhaustive stair ascent for evacuation. Data were collected by a three-dimensional motion capture system synchronized with EMG and force plate when walking upwards on a 10° inclined walkway.The significantly (p≤0.05) decreased EMG median frequencies of tibialis anterior during early (ES) and late stance (LS) phases, and vastus lateralis muscles during LS are the evidence of leg local muscle fatigue (LMF). The perpendicular and longitudinal shear GRFspeaks were significantly reduced during ES (p≤0.05) and LS (p≤0.01), respectively. The post-fatigue SP, SL, and SDN were significantly (p<0.05) shorter. Specially, the foot anglemins, ankle anglepeaks, and relevant angvelx peaks, and angaccx peaks significantly (p≤0.05) decreased in post-fatigue trials. The post-fatigue RCOFpeaks were found significantly (p≤0.01) lower during LS phase. Thus, whole body exhaustion and leg LMF constrained the gait kinetics and kinematics when walking upwards indicating a cautious gait associated with the risks of falls, accidents, which can hinder the process of evacuation and work safety on slopes.
|
|
| 8. |
|
|
| 9. |
- Halder, Amitava, et al.
(author)
-
Gait Biomechanics While Walking Down an Incline After Exhaustion
- 2023
-
In: Fire Technology. - 1572-8099. ; 59:4, s. 1833-1863
-
Journal article (peer-reviewed)abstract
- This gait biomechanics study investigated stride length (SL), stride duration (SDN), the peak values of ground reaction forces (GRFspeak), required coefficient of friction (RCOFpeak), leg joints’ angles (anglepeak), angular velocity (angvelx.peak), angular acceleration (angaccx.peak), minimum angle (anglemin.) of the foot, and muscles’ electromyography (EMG) during the stance phase (SP) of the dominant leg following an exhaustive stair ascent on a stair machine. Data were collected by a three-dimensional motion capture system synchronized with EMG and force plate while walking down a 10° inclined stationary walkway. Although the leg muscles’ EMG showed no significant local muscle fatigue (LMF) during post-exhaustive walking downwards, the SL was significantly (p < 0.05) shorter than the pre-exhaustive. The mean vertical GRFzpeak. was significantly (p ≤.01) reduced during late stance (LS) phase, however, the antero-posterior GRFypeak. was found to be significantly (p ≤ 0.01) higher. The RCOFpeak. was significantly (p ≤.05) higher during the post-exhaustive walking downwards, LS phase. The available coefficient of friction value of ~ 0.350 seems to be the RCOF to reduce slips and falls on an inclined dry surface. None of the post-exhaustive lower limb joints’ anglepeak, anglemin., ang.velx.peak, and ang.accx.peak were significantly changed in post-exhaustion walking, except the knee ang.accx.peak., which was significantly (p < 0.05) increased during the LS period. The constrained post-exhaustive gait biomechanics indicate a perturbed gait, which may increase the risks for slips and fall-related accidents, when walking downwards and working on slopes. However, the non-significant joint angle changes imply that walking down is less demanding in a kinesiological perspective compared to walking up an incline.
|
|
| 10. |
- Halder, Amitava, et al.
(author)
-
Limitations of oxygen uptake and leg muscle activity during ascending evacuation in stairways
- 2017
-
In: Applied Ergonomics. - : Elsevier BV. - 0003-6870. ; 66, s. 52-63
-
Journal article (peer-reviewed)abstract
- Stair ascending performance is critical during evacuation from buildings and underground infrastructures. Healthy subjects performed self-paced ascent in three settings: 13 floor building, 31 floor building, 33 m stationary subway escalator. To investigate leg muscle and cardiorespiratory capacities and how they constrain performance, oxygen uptake (VO2), heart rate (HR) and ascending speed were measured in all three; electromyography (EMG) in the first two. The VO2 and HR ranged from 89-96 % of the maximum capacity reported in the literature. The average highest VO2 and HR ranged from 39-41 mL·kg-1·min-1 and 162-174 b·min-1, respectively. The subjects were able to sustain their initial preferred maximum pace for a short duration, while the average step rate was 92-95 steps·min-1. In average, VO2 reached relatively stable values at ≈37 mL·kg-1·min-1. EMG amplitudes decreased significantly and frequencies were unchanged. Speed reductions indicate that climbing capacity declined in the process of fatigue development. In the two buildings, the reduction of muscle power allowed the subjects to extend their tolerance and complete ascents in the 48 m and 109 m high stairways in 2.9 and 7.8 minutes, respectively. Muscle activity interpretation squares were developed and proved advantageous to observe fatigue and recovery over time.
|
|
