Science

Unipedaling is backed by comprehensive research and we hope that you will get excited  as us when reading the promising results below or downloading our white paper.

If you enjoy listening to podcasts, we recommend The Training Science Podcast where Professor Paul Laursen interviews Professor Jim Martin from the University of Utah and talk about the best kept secret in cycling training - assisted single leg cycling.

Background

The science behind single leg cycling dates back to at least the 1950's when the first paper was published from a research group in Sweden. They concluded that the work capacity per leg is greater when pedaling with one compared to two legs. This is the product of the cardiovascular system only having to provide oxygen to half the muscle mass. We call this increased work capacity "aerobic hyperpower".

However, only pedaling with one leg without assistance in the upstroke is straining, because the other leg is otherwise “assisting” by pushing in its downstroke. This leads to fatigue that shortens the duration that one-legged pedaling can be performed and makes it difficult to reach “aerobic hyperpower” at all. It is therefore paramount to use some kind of method to create a more natural pedal stroke when only using one leg. Over the years several methods have been used to achieve this, which have their specific limitations that The Unipedal solves with its spring based design.

Physiology

The increased work capacity of the muscles or "aerobic hyperpower" generates a stronger stimulus for the muscles to adapt to the training. The conclusions of a 2011 study conducted by a number of high level researchers in the field of exercise physiology and sports performance highlights this effect. For example, they showed that high-intensity interval training (HIIT) with one leg at a time yields greater increases in mitochondrial proteins (such as COX II and COX IV) and the glucose transport protein GLUT-4 compared to conventional two-legged pedaling.

In a paper from 2020 a different research group notes that assisted single-leg cycling is a potent but underutilized training method, which they speculate is due to the lack of commercially available devices. With The Unipedal, this has changed.

Age

There is at the moment no research on children or youth athletes, which is why we do not recommend unipedaling for this group. For adults, there is currently no evidence to support that unipedaling should be performed differently for different age groups. At least not different compared to the general impact aging has on training, from about 35 years of age and onward, where athletes do not have the same exercise capacity and therefore have to adapt the intensity and volume of training to their individual needs. However, a paper from Haddad et al (2024) suggests that older people (~65 year olds) enjoy a larger initial “aerobic hyperpower” effect from unipedaling compared to younger (~35 year olds).

Altitude and heat

According to demographic research from Tremblay & Ainslie (2021), approximately 500 million people live at an altitude above 1500 meters and 8 million just in the USA. For athletes using altitude training or living at altitude, Draper et al (2022) has shown that unipedaling "offsets the reduced muscle oxygenation in hypoxic environments".

There is at the moment no research on unipedaling in a hot environment, but in theory the effect should be similar to altitude as the reductions in work capacity in both conditions depend on similar mechanisms of reduced oxygen delivery to the muscles. It is therefore reasonable to speculate that unipedaling can improve the effectiveness of heat training or training quality during prolonged exposure to high temperatures, e.g. a summer heat wave.

Rehabilitation

Unipedaling has been shown to be a useful training modality during a period of injury affecting one leg and re-training after these types of injuries. A research group at the university of Lille Nord du France, led by Nicolas Oliver, have concluded that:

• 1-leg cycling may be more easily tolerated than arm cranking by patients participating in aerobic conditioning after knee surgery.

• After knee surgery, conventional rehabilitation does not limit cardiorespiratory deconditioning. One leg cycling appears to be an adapted method to stop the effects of hypoactivity.

Critisism and alternative methods

References

Abbiss et al (2011): Single-leg cycle training is superior to double-leg cycling in improving the oxidative potential and metabolic profile of trained skeletal muscle

Asmussen et al (2023): Counterweight mass influences single-leg cycling biomechanics

Bassett & Howley et al (2000): Limiting factors for maximum oxygen uptake and determinants of endurance performance

Bell, G et al (1988): The influence of one-legged training on cardiorespiratory fitness

Bini et al (2015): Comparison of kinetics, kinematics, and electromyography during single-leg assisted and unassisted cycling

Bini et al (2016): Joint Torques and Patellofemoral Force During Single-Leg Assisted and Unassisted Cycling

Bisconti et al (2023): Efficacy of small muscle mass exercise training to promote health

Bjørgen et al (2009): Aerobic high intensity one and two legs interval cycling in chronic obstructive pulmonary disease: the sum of the parts is greater than the whole

Bjørgen et al (2009): Aerobic high intensity one-legged interval cycling improves peak oxygen uptake in chronic obstructive pulmonary disease patients; no additional effect from hyperoxia

Bossi et al (2016): No differences in gross efficiency between dominant and non-dominant legs during one-legged counterweighted cycling

Burns, K J et al (2014): Cardiovascular responses to counterweighted single-leg cycling: implications for rehabilitation

Burns, K J et al (2014): Response to Letter to the Editor: a counterweight is not necessary to implement simple, natural and comfortable single-leg cycle training

Cardinale, D A & Ekblom, B (2018): Hyperoxia for performance and training

Cardinale, D A et al (2019): Influence of Hyperoxic-Supplemented High-Intensity Interval Training on Hemotological and Muscle Mitochondrial Adaptations in Trained Cyclists

Chester (1999): Sympathetic adaptation to one-legged training

Cooper Bagley et al (2020): Single leg aerobic capacity and strength in individuals with surgically repaired anterior cruciate ligaments

Del Torto et al (2021): Effect of small vs large muscle mass endurance training on maximal oxygen uptake in organ transplanted recipients

Dolmage & Goldstein (2008): Effects of one-legged exercise training of patients with COPD

Dolmage & Goldstein (2006): Response to one-legged cycling in patients with COPD

Dolmage, T E et al (2014): A counterweight is not necessary to implement simple, natural and comfortable single-leg cycle training

Draper et al (2022): Single Leg Cycling Offsets Reduced Muscle Oxygenation in Hypoxic Environments

Duner (1959): Oxygen Uptake and Working Capacity in Man During Work on the Bicycle Ergometer With One and Both Legs

Elmer et al (2012): Fatigue is specific to working muscles: no cross-over with single-leg cycling in trained cyclists

Elmer et al (2015): Biomechanics of Counterweighted One-Legged Cycling

Elmer & Martin (2021): Metabolic power and efficiency for an amputee cyclist: implications for cycling technique

Evans et al (2015): One-Legged Cycle Training for Chronic Obstructive Pulmonary Disease. A Pragmatic Study of Implementation to Pulmonary Rehabilitation

Faulhaber et at (2023): Repeated Short-Term Bouts of Hyperoxia Improve Aerobic Performance in Acute Hypoxia

Freitag, N et al (2020): Is Structured Exercise Performed with Supplemental Oxygen a Promising Method of Personalized Medicine in the Therapy of Chronic Diseases?

Gleser M A (1973): Effects of hypoxia and physical training on hemodynamic adjustments to one-legged exercise

Gordon, N et al (2018): Active and Inactive Leg Hemodynamics during Sequential Single-Leg Interval Cycling

Gordon, N et al (2019): High-Intensity Single-Leg Cycling Improves Cardiovascular Disease Risk Factor Profile

Gordon, N et al (2020): Single-leg cycling increases limb-specific blood flow without concurrent increases in normalised power output when compared with double-leg cycling in healthy middle-aged adults

Haddad et al (2024): The Improvement in Exercise Performance during Reduced Muscle Mass Exercise is Associated with an Increase in Femoral Blood Flow in Older and Younger Endurance-Trained Athletes

Heidorn et al (2023): Single-leg cycling to maintain and improve function in healthy and clinical populations

Iannetta et al (2019): Interlimb differences in parameters of aerobic function and local profiles of deoxygenation during double-leg and counterweighted single-leg cycling

Kilding, A E et al (2012): Effect of hyperoxic-supplemented interval training on endurance performance in trained cyclists

Layec, G & Richardsson, RS (2012): Training to improve performance: one leg at a time

LaScola, P et al (2020): Physiological Responses to Counterweighted Single-Leg Cycling in Older Males

LeJemtel et al (1986): Failure to augment maximal limb blood flow in response to one-leg versus two-leg exercise in patients with severe heart failure

MacInnis et al (2017): Superior mitochondrial adaptations in human skeletal muscle after interval compared to continuous single-leg cycling matched for total work

MacInnis et al (2017): Physiological responses to incremental, interval, and continuous counterweighted single-leg and double-leg cycling at the same relative intensities

MacInnis et al (2019): The effect of short-term, high-intensity exercise training on human skeletal muscle citrate synthase maximal activity: single versus multiple bouts per session

Mallette, MM et al (2018): The Effects of Hyperoxia on Sea-Level Exercise Performance, Training, and Recovery: A Meta-Analysis

Manca et al (2018): Neurophysiological adaptations in the untrained side in conjunction with cross-education of muscle strength: a systematic review and meta-analysis

Menz et al (2016): Cardiorespiratory Effects of One-Legged High-Intensity Interval Training in Normoxia and Hypoxia: A Pilot Study

Munch et al (2017): Effect of 6 weeks of high-intensity one-legged cycling on functional sympatholysis and ATP signaling in patients with heart failure

Neary & Wenger (1986): The effects of one- and two-legged exercise on the lactate and ventilatory threshold

Neunhäuserer, D et al (2023): The Impact of Exercise Training and Supplemental Oxygen on Peripheral Muscles in Chronic Obstructive Pulmonary Disease: A Randomized Controlled Trial

Odden et al (2024: The higher the fraction of maximal oxygen uptake is during interval training, the greater is the cycling performance gain

Olivier et al (2008): One-Leg Cycling Versus Arm Cranking: Which is Most Appropriate for Physical Conditioning After Knee Surgery?

Oliver et al (2008): One-leg cycling aerobic training with the healthy leg in amateur soccer players after anterior cruciate ligament reconstruction

Olivier et al (2009): Effect of One-Leg Cycling Aerobic Training in Amateur Soccer Players After Anterior Cruciate Ligament Reconstruction

Oliver et al (2010): The effect of a one-leg cycling aerobic training program during the rehabilitation period in soccer players with anterior cruciate ligament reconstruction

Pageaux et al (2016): Reliability of a Novel High Intensity One Leg Dynamic Exercise Protocol to Measure Muscle Endurance

Pengyuan, L et al (2025): Effects of hyperoxic training on red blood cell deformability and mechanical properties in elite male endurance athletes: A randomized crossover study

Perry, C et al (2007): The effects of training in hyperoxia vs. normoxia on skeletal muscle enzyme activities and exercise performance

Ponsot et al (2010): Impairment of maximal aerobic power with moderate hypoxia in endurance athletes: do skeletal muscle mitochondria play a role?

Przyklenk et al (2017): Endurance Exercise in Hypoxia, Hyperoxia and Normoxia:

Mitochondrial and Global Adaptations

Ray, C A (1999): Sympathetic adaptations to one-legged training

Rud et al (2012): One-legged endurance training: leg blood flow and oxygen extraction during cycling exercise

Scalzo et al (2022): Single-leg exercise training augments in vivo skeletal muscle oxidative flux and vascular content and function in adults with type 2 diabetes

Skattebo et al (2020): Contribution of oxygen extraction fraction to maximal oxygen uptake in healthy young men

Skattebo et al (2022): Increased Mass-Specific Maximal Fat Oxidation Rate with Small versus Large Muscle Mass Exercise

Sperlich et al (2017): The Impact of Hyperoxia on Human Performance and Recovery

Staples et al (2020): Emphasizing One Leg Facilitates Single-Leg Training Using Standard Cycling Equipment

Ting et al (1998): Sensorimotor state of the contralateral leg affects ipsilateral muscle coordination of pedaling

Tremblay & Ainslie (2021): Global and country-level estimates of human population at high altitude

Ulrich et al (2017): Mechanisms of Improved Exercise Performance under Hyperoxia

Wezenberg et al (2011): Feasibility and Validity of a Graded One-Legged Cycle Exercise Test to Determine Peak Aerobic Capacity in Older People With a Lower-Limb Amputation

Zhang et al (2021): Exercising muscle mass influences neuromuscular, cardiorespiratory, and perceptual responses during and following ramp-incremental cycling to task failure