Image Source: Wikimedia Commons
What muscle groups are used while mountain biking?
The muscles of the buttock, hamstrings, quads, calf, shoulder, chest, arms & forearms and the core muscles are all heavily involved while mountain biking.
Lower-body muscles & MTB
The quadriceps push the pedal down towards the trail/path while the calf muscles work in opposition to the quads, bringing the foot back upward to the bent position.
The hamstrings work in conjunction with the calf to pull the leg up, while the muscles of the buttock move the thigh forward and keep the rider stable along with the abdominals and ‘core’ muscles.
Your rectus abdominis and other “core” muscles work together to stabilize you while your descending and climbing single-track (Image Source)
Upper body muscles & MTB
The biceps help stabilize the rider and helps lift or pull on the handlebars.
While the triceps and pectoral muscles aid with stability, especially during descents and from ground vibrational forces.
The forearms are responsible for braking, shifting and gripping and are absolutely vital during mountain biking.
Muscles of the forearm - These muscles are extensively used during long and technical downhilling (image source)
Muscles used during Pedal cycle
The pedal stroke is usually broken down into two phases, the power or propulsive phase, and the recovery phase. Let us look at the specific muscle groups used while pedaling in these 2 phases.
The 2 phases of the pedal cycle
1) Power (propulsive) phases: 0° (top dead center) to 180° (bottom dead center)
Gluteus maximus: Main glute contribution from 0° - 45° (almost used exclusively to extend the hip during this range)
Hamstring group: Primary ‘hammy’ contribution from 135° to 180° (biceps femoris primary in this pedaling range)
Gluteus maximus AND hamstrings work together: 45° to 125°
Vastus lateralis: Largest and most powerful ‘quad’ muscle: Most active from ~315° to 105°
Vastus medialis: Another ‘quad’ muscle that is most active from 315° to 105°
Soleus (muscle of the calf): Most active ~30° to 145°
Gluteus maximus (Image Source: Wikimedia Commons)
2) Recovery phase: 180° of crank rotation back to 360°
Iliopsoas: Flexes the thigh during the recovery phase. The iliopsoas is the strongest of the hip flexor muscles and is used more so during strenuous pedaling
The iliopsas is comprised of both your illacus and psoas major msucles (Image Source: Wikimedia Commons)
3) Muscles used during both phases of the pedal cycle
Vastus lateralis: Largest and most powerful “quad” muscle: Most active from 315° to 105°
Vastus medialis: Another “quad” muscle that is most active from 315° to 105°
Gastrocnemius (calf muscle) active from 35° to 260° of the pedal cycle
Rectus Femoris: Active during the first 60° of Power phase and re-activated during the recovery phase at 180° the RF contracts to assist in flexion of the hip.
Tibialis anterior (shin muscle) - Contracts from about 270° to ~90° - The shin muscle raises the foot and is activated during upward movement of the pedal before the ‘dead point’
Vastus lateralis, the largest and most powerful “quad” muscle (Image Source: Wikimedia Commons)
Muscles Used & Ranges of Muscle Activation
The muscles used during the pedal stroke and the degree ranges are more theoretical and provide a rough approximation. Most calculations were created by researchers in laboratory-type settings. However, in the real world, hills, cycling cadence, body position on the bike, length of ride, seat height variations, variable surface terrain, fatigue, & mechanical issues all play a role. But this provides a good reference point.
“The quadriceps are hugely responsible for ‘pedal power’ ”
What are the ‘quads’?
The quadriceps are the muscles on the front part of the leg above the knee. They are called ‘quads’ since 4 muscles make up the quadriceps:
Rectus femoris
Vastus intermedius
Vastus lateralis
Vastus medialis
The L’s are the physical shape of Chile.
Road cycling vs Singletrack MTB riding
“Unlike road-based cycling disciplines, MTB involves more dynamic movements of the upper body to manoeuvre the bicycle over and around obstacles and to aid the dampening of trail shocks””
Road cycling uses mostly lower body muscle groups. Mountain biking singletrack & MTB trails with rough and varying terrain requires muscles of the upper body to work, particularly when ascending and descending steep terrain:
Rotator cuff muscles - Helps you make all shoulder and arm motions. MTB riding helps stabilize the shoulder joint. Used in shock absorption while riding bumpy and rocky singletrack / MTB trails. Helps pull arm towards body towards rider while pedaling uphill out of the saddle
Deltoid - Help raise and lower the arm. Muscles used during standup riding and help in shock absorption during steep descents
Trapezius - Raises and supports the shoulder, especially when riding out of the saddle
Latissimus dorsi - The ‘lats’ assist in rider balance
Triceps - Vital for stability while descending single & double-tracks. The triceps work eccentrically while providing shock absorption to the rider
Biceps brachii - The biceps help stabilize the rider and help lift or pull on the handlebars
Forearm (brachioradialis especially) - The forearms are hugely important in MTB, and play a huge role in braking and balancing, especially during steep and fast descents.
Serratus anterior - Assists the ‘pecs’ with shoulder abduction by pulling the shoulder blades forward. Involved in shock absorption
Pectoralis muscles - The ‘pecs’ help to abduct the shoulders. Help with rider stability, especially during downhill descents, along with sections that require the rider to be in a standing position to help absorb trail shocks (bumps)
Muscle groups & Ideal pedal stroke
Muscle groups used during IDEAL pedal stroke(image source)
So what makes one pedal stroke better than another pedal stroke? Two primary factors determine pedal stroke:
Saddle height
Saddle position (forward or rearward)
Many people ride with the seat too low or forward, which increases the knee flexion angle leading to greater compressive forces from the quadriceps. This basically means that the ‘quads’ are overworked and the large butt and hamstring muscles are underused, along with under-activation of the calf muscles.
If you look at the image, you notice that the glutes and hamstring muscles should be primary movers, along with the quadriceps.
wheel size and muscle activation
Several studies have looked at the differences between 26, 27.5, and 29ers and have some pretty clear conclusions. What have these studies found?
Larger wheel diameters did not significantly reduce muscle activity or vibrations. However, the study noted that 26” wheels had greater bicep activity, which the researchers theorized that the smaller wheels needed to be lifted over obstacles. How much more bicep activity? About 1/3 more, or approximately 30% more bicep participation.
The larger 27.5 and 29ers MTBs would have just rolled over the smaller obstacles that affected the 26er.
Muscular activity during uphill pedaling
A 2008 study from the Journal of Electromyography and Kinesiology looked at the differences in muscular activity with varying degrees of steepness (4%, 7%, and 10 % slope percentage). Let us review some of the findings from this study:
The muscular activity of both the upper and lower body was relatively the same between all 3 levels of steepness
The muscles of the arms and trunk were heavily involved while standing as opposed to pedaling from the saddle, especially an increase in muscular activation of the gluteus maximus and the transverse abdominal muscle (TVA)
Conclusion
Mountain biking, especially under more strenuous and varied riding conditions uses almost all of the muscles of the body. While the hamstrings, glutes, quadriceps, and calf muscles of the lower body propel the MTB forward, the pectorals, the “core,” triceps, deltoid complex, biceps, and forearms muscles all keep the body stable and on the bike during downhill descents and help absorb trail shocks.
Jesse (Director of Pedal Chile) lives in Chile’s Patagonia. Jesse has a Master of Science in Health and Human Performance, and a Bachelor of Science in Kinesiology. Hobbies: Riding the single-track down the active volcano near Pucón and an avid reader and blogger for Pedal Chile.
References:
Achim Schmidt (2014). Mountain bike training for all levels of performance. Maidenhead Meyer & Meyer Sport.
da Silva, J.C.L., Tarassova, O., Ekblom, M.M. et al. Quadriceps and hamstring muscle activity during cycling as measured with intramuscular electromyography. Eur J Appl Physiol 116, 1807–1817 (2016). https://doi.org/10.1007/s00421-016-3428-5
Duc, S., Bertucci, W., Pernin, J.N. and Grappe, F. (2008). Muscular activity during uphill cycling: Effect of slope, posture, hand grip position and constrained bicycle lateral sways. Journal of Electromyography and Kinesiology, 18(1), pp.116–127.
Evens T, Dano J. E. Effects of Saddle Alignment and Pedal Stroke Training on a Competitive Cyclist with Anterior Knee Pain: A Case Report. Internet Journal of Allied Health Sciences and Practice. 2019 Jun 28;17(3), Article 3.
Hurst, Howard Thomas , Swarén, Mikael, Hébert-Losier, Kim, Ericsson, Fredrik, Sinclair, Jonathan Kenneth , Atkins, Stephen and Holmberg, Hans-Christer (2012) Influence of Course Type on Upper Body Muscle Activity in Elite Cross-Country and Downhill Mountain Bikers During Off Road Downhill Cycling. Journal of Science and Cycling (JSC), 1 (2). pp. 2-9.
Hurst, Sinclair, J, Atkins, S, Rylands, LP and Metcalfe, J. Influence of wheel size on muscle activity and tri-axial accelerations during CrossCountry mountain biking. Journal of Sport Sciences, 2016.
Mcknight, J. (2012). Mountain biking : skills, techniques, training. Ramsbury, Marlborough, Wiltshire: The Crowood Press.
Wozniak Timmer, C.A. (1991). Cycling Biomechanics: A Literature Review. Journal of Orthopaedic & Sports Physical Therapy, 14(3), pp.106–113.