Another really nice study was just published in “Archives of Physical Medicine and Rehabilitation”. The study from Vinstrup et al. 2015 examines differences in muscle activation during knee flexion- and extension with two different training modalities; conventional machine training and Theraband elastic tubing.
Physiotherapists working with chronic stroke patients should use this knowledge to apply best practices of rehabilitation following stroke. More on this topic will follow.
To investigate whether elastic resistance training can induce comparable levels of muscle activity as conventional machine training in chronic stroke patients.
Outpatient rehabilitation facility
18 stroke patients with hemiparesis (mean age 57 (SD: 8) years).
Patients performed 3 consecutive reps at 10 repetition maximum (RM) of unilateral knee extension- and flexion, using elastic resistance and conventional training machines.
Main outcome measure
Surface electromyography (EMG) was measured in vastus lateralis (VL), vastus medialis (VM), biceps femoris (BF) and semitendinosus (ST), and normalized to the maximal EMG (nEMG) of the non-paretic leg.
In the paretic leg, agonist muscle activity ranged from 18-24% nEMG during knee flexion and 32-40% nEMG during knee extension. For the latter, VL nEMG was higher during machine exercise compared with elastic resistance (40% [95% CI 33 – 47] vs 32% [95% CI 25 – 39], P=0.003). In the non-paretic leg, agonist muscle activity ranged from 54-61% during knee flexion and 52-68% during knee extension (n.s.). For knee flexion, ST nEMG was higher (61% [95% CI 50 – 71] vs 54% [95% CI 44 – 64], P=0.016), and for knee extension VM nEMG was higher (68% [95% CI 60 – 76] vs 56% [95% CI 48 – 64], P<0.001) during machine exercise compared with elastic resistance. By contrast, antagonist co-activation was significantly higher during knee flexion with elastic resistance compared with the machine. Lastly, there were no differences in perceived exertion between exercise modalities.
Machine training appears to induce slightly higher levels of muscle activity in some of the investigated muscles compared to elastic resistance during lower-limb strength training in chronic stroke patients. The higher level of co-activation during knee flexions with elastic tubing suggests that elastic resistance exercises are more difficult to perform. This is likely due to a higher level of movement instability.