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Duc, S., Bertucci, W., Pernin, J., & Grappe, F. (2008, February). Muscular activity during uphill cycling: Effect of slope, posture, hand grip position and constrained bicycle lateral sways. Journal of Electromyography & Kinesiology, 18(1), 116-127.
QUOTED ABSTRACT
Abstract: Despite the wide use of surface electromyography (EMG) to study pedalling movement, there is a paucity of data concerning the muscular activity during uphill cycling, notably in standing posture. The aim of this study was to investigate the muscular activity of eight lower limb muscles and four upper limb muscles across various laboratory pedalling exercises which simulated uphill cycling conditions. Ten trained cyclists rode at 80% of their maximal aerobic power on an inclined motorised treadmill (4%, 7% and 10%) with using two pedalling postures (seated and standing). Two additional rides were made in standing at 4% slope to test the effect of the change of the hand grip position (from brake levers to the drops of the handlebar), and the influence of the lateral sways of the bicycle. For this last goal, the bicycle was fixed on a stationary ergometer to prevent the lean of the bicycle side-to-side. EMG was recorded from M. gluteus maximus (GM), M. vastus medialis (VM), M. rectus femoris (RF), M. biceps femoris (BF), M. semimembranosus (SM), M. gastrocnemius medialis (GAS), M. soleus (SOL), M. tibialis anterior (TA), M. biceps brachii (BB), M. triceps brachii (TB), M. rectus abdominis (RA) and M. erector spinae (ES). Unlike the slope, the change of pedalling posture in uphill cycling had a significant effect on the EMG activity, except for the three muscles crossing the ankle’s joint (GAS, SOL and TA). Intensity and duration of GM, VM, RF, BF, BB, TA, RA and ES activity were greater in standing while SM activity showed a slight decrease. In standing, global activity of upper limb was higher when the hand grip position was changed from brake level to the drops, but lower when the lateral sways of the bicycle were constrained. These results seem to be related to (1) the increase of the peak pedal force, (2) the change of the hip and knee joint moments, (3) the need to stabilize pelvic in reference with removing the saddle support, and (4) the the shift of the mass centre forward.
NOTES
Authors noted a lack of prior research on uphill cycling, especially standing.
Li and Caldwell (1998) previously reported monarticular muscles are more affected by standing than bi-articular.
Contains a good review of the standing research related to torque and muscle activity.
Good review of Caldwell and Clarys studies that examined torque and EMG at climbing gradients.
Tires at 700 kPa. PowerTab hub used. Subjects own racing bike.
Torso angles were not controlled. Saddle height not controlled. Cadence was different between cyclists (but not trials) even though they indicated cadence differences as a shortcoming in Caldwell and Clarys studies. Basically used a self-selected cadence but kept this the same for all trials.
Use a MAP test that started at 125 W at 1%, increasing 30 W and .5% grade every 2 min. Power output was 80% of MAP for trials. Approx 300W based on average of 378W for subjects.
Self-selected warm-up period.
Cadence differed between cyclists (60-70 rpm) but not between trials.
Each trial was 1 min separated by 3 min of low active recovery.
Intensity and timing of muscle contraction were not significantly different for the slopes studied (4%, 7% and 10%), except for GM and ES during standing.
Chart on p 121. shows the table of activity time in relation to crank arm angle.
Recommend using rollers or motorised treadmill because of the trainer's influence of constraints to lateral sway. Difficulties in maintaining balance while standing on rollers may lead to potential effects on pedalling technique.
Only 4% of variables were influenced by change in slope, which were in line with Li and Caldwells findings that no difference in EMG. Authors indicate the effect of slope could be masked because of a lower cadence in the Li and Caldwell study. The global activity differences reported by Clarys were not supported by this study. However, only 4 muscles were used by Clarys (VM, GAS, TA, and BF) and when these only were examined from the Duc data, significant differences were found. NOTE: caution that the number of lower leg muscles used may effect global results.
Advantages of indoor treadmill
1. Air resistance eliminated.
2. Air resistance to wheel rotation was constant
3. Pedal speed constant
4. Mechanical power requirement was constant for each subject (p. 123)
EMG activity of the TF and TA increased on a trainer. Also, global intensity of lower limb was higher. Possible that EMG is more affects by change of pedalling posture on a trainer, which constrains sway.
During standing, GM has a longer duration of activation. Also, RF activity during second part of down stroke increased. VM is activated earlier in upward recovery and lasts longer into the downward power phase. Activity of SM decreased inexplicably.
Short report near the end of a study by Antonis (1989) that included a changing fore-aft saddle on climbing from 0 to 20%. Indicated decreased muscle activity mainly in arms. Benefits to short legged athletes with saddle forward but long legged cyclists were more economical with saddle in backward position (67% seat tube angle).
Main effect of hand position from brake levers to drops was in standing is the increase of arm muscle activity mainly due to weight support with torso more level and center of gravity farther forward. There is also a decrease in RF activation likely due to reduction in hip angle. This article relays finding on hip angles from Savelberg et al (2003) and Juker et al. (1998).
Cyclists often switch between postures when climbing, yet this study shows increase in muscle activation except at the ankle joint. Also an increase in upper body muscle activity to stabilize the torso. This should all lead to greater energy expenditure. Research by Tanaka eta al (1996) and Ryschon and Stray-Gundersen (1991) indicate increase in VO2 between uphill seated and standing postures. Yes, other studies did not find significant differences for gross efficiency and economy at 75% MAP or Vo2max (Millet et al. 2002; Swain and Wicox 1992). Also, at high intensity Tanaka (1996) showed similar VO2 responses standing and seated. Duc et al. postulates the following reasons for why cyclists standing in spite of the higher energy expenditures:
1. It is perceived to be less difficult because of redistribution of workload over grater muscle mass.
2. Alteration of force-velocity and force-length relationships of power producer muscles
3. or, availability to generate greater power using non-muscular force like gravity.
Cyclists are able to use 2 distinct muscle chains. Recommended coaches advise cyclists to train in standing climb mode. Also, strengthen the arm and trunk power. Recommend alternating standing and seated on long climbs.
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Li, L., & Caldwell, G.E. (1998, September). Muscle coordination in cycling: effect of surface incline and posture. Journal Of Applied Physiology, 85(3), 927-934.
Quoted Abstract
The purpose of the present study was to examine the neuromuscular modifications of cyclists to changes in grade and posture. Eight subjects were tested on a computerized ergometer under three conditions with the same work rate (250 W): pedaling on the level while seated, 8% uphill while seated, and 8% uphill while standing (ST). High-speed video was taken in conjunction with surface electromyography (EMG) of six lower extremity muscles. Results showed that rectus femoris, gluteus maximus (GM), and tibialis anterior had greater EMG magnitude in the ST condition. GM, rectus femoris, and the vastus lateralis demonstrated activity over a greater portion of the crank cycle in the ST condition. The muscle activities of gastrocnemius and biceps femoris did not exhibit profound differences among conditions. Overall, the change of cycling grade alone from 0 to 8% did not induce a significant change in neuromuscular coordination. However, the postural change from seated to ST pedaling at 8% uphill grade was accompanied by increased and/or prolonged muscle activity of hip and knee extensors. The observed EMG activity patterns were discussed with respect to lower extremity joint moments. Monoarticular extensor muscles (GM, vastus lateralis) demonstrated greater modifications in activity patterns with the change in posture compared with their biarticular counterparts. Furthermore, muscle coordination among antagonist pairs of mono- and biarticular muscles was altered in the ST condition; this finding provides support for the notion that muscles within these antagonist pairs have different functions.
Notes
Graham and Caldwell show difference in muscle activity standing.
Indicates only a few studies on cycling and incline. Alvarez (1996) A new bicycle pedal. ., Despires (1974) An electromyographic study. . ., Faria & Cavanagh (1978) book The physiology and biomechanics of cycling.
Gregor studies 1991, 1985, 1982
Used a velodyne trainer in study.
Used equation for pedal kinematics by Coyle et al (1991) physiological & biomechanical. . .
Caldwell (1996) showed lower extremity joint moments changed during uphill cycling.
The increase in Gluteus Maximus EMG activity while standing was not a result of greater hip extensor moment.
Found no different in EMG for ankle plantar flexion when standing even though peak plantar flexor moment increased. Speculated that perhaps this is from gastrocnemious being biarticular.
Findings support the difference in mono and bi-articular muscles in cycling theorized by Schenau and supported by other research.
Subjects used biceps femoris muscle differently while standing, even for the same task. Perhaps due to pedal style (fixed vs flexing ankle).
Muscle strength possibly a factor with weaker on-joint hip extensors leading to more help from biceps femoris. Conversely, on-joint hip associated with increased rectus femoris activity.
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