Can Cross Training On A Bike Translate To Better Running Performance?

Picture from Bikatadventures.com

I had shin stress fractures in both legs from running too much when I was 20. The doctor I saw said that I could not run for a minimum of 6 weeks. I could only swim or bike. It was this cross training regime that got me started in triathlon later.

This concept cross training emerged in the 1980s along with the popularity of triathlon. Earlier studies reported that performance in a primary sport can be maintained despite reductions in volume of the primary sport by training in a variety of sports. These findings suggest potential crossover effects between endurance training modalities. Are these findings still relevant?

The following systematic review by Menges et al (2026) compared the effects of running only and cycling only training interventions to evaluate cross training transfer to sport specific VO2 max and running performance.

The authors found 7 studies with intervention durations of at least 4 weeks. These were run only training with cycling only or combined running-cycling interventions. Outcomes included VO2 max assessed on a treadmill or cycle ergometer as well as running time trial performance for 1 mile, 3000m and 5000m.

So does cross training on a bike help running performance? This meta-analysis suggests it does. The subjects who performed run only, bike only or combined running and cycling training performed similarly in the 1 mile, 3000m and 5000m time trials. They also had improved VO2 max values regardless of testing method (treadmill or cycle ergometer).

Cycling engages the quadriceps and gluteus maximus muscles in ways that running does not. When the muscles get stronger, it helps improve running economy and power (especially in hilly races).

Instead of running twice a day, you can take away some of the extra strain on the legs by cycling (or even training on the elliptical machine) without the repetitive impact forces of running. This is especially beneficial during recovery periods or for runners prone to injuries.

Cycling is low impact which is great for your joints. However, it does little to help your bone density. Running on the other hand has impact loading that helps to maintain or even increase bone strength which is great for older athletes.

The findings should be interpreted with some caution since there were limited studies (7) and the fairly short training period.

For shorter distances up to 5 km at least, there may not be any differences but in a longer event like the marathon, you still need to run since the run muscles will not used as much while cycling. Biking can definitely help the aerobic fitness but not the specific leg muscles, and running performance may decline.

Running and cycling can actively enhance each other when integrated carefully. If you're a runner looking to improve your endurance without extra impact or a cyclist looking for stronger stabilizing muscles, cross training helps.

The key is balancing both to meet your specific training goals while avoiding overuse injuries.

The principle of specificity suggests that cross training can offer general fitness benefits, the most significant performances are achieved through sport specific training. Before Sabastian Sawe broke the 2 hour barrier for the marathon, he was running in excess of 200 km a week in the 6 weeks leading up to London, with a maximum of 241 km (150 miles). 

So, runners and cyclists should incorporate cross training as a supplementary activity rather than a replacement for their primary sport.

References

Menges T, Dindorf C, Dully J et al (2026). Cross-Training Between Rnning And Cycling: Effects On VO2 Max And Running Performance- A Systematic Review And Meta-Analysis. Front Sp Act Living. 8: 1843803. DOI: 10,3389/fspor.2026.1843803

Tanaka H. (1994). Effects Of Cross-Training. Sports Med. 18: 330-339. DOI: 10.2165/00007256-199418050-00005

Carbon Plated Shoes And Stress Fractures

Picture from Prodirectsport

I just saw 3 different people wearing carbon plated shoes at the Cold Storage in Holland Village. They were shopping for groceries and definitely not running. On one hand you have someone like me who's still unwilling to run in carbon plated shoes while on the other hand they are a dime a dozen amongst runners now (and people walking in Cold Storage). Most runners use them in training as well, not just at races. 

No running study has studied whether carbon plated shoes (known as advanced footwear technology or AFT) changes running biomechanics associated with bone stress injuries (BSI), or shin splints. The researchers goals were to measure running biomechanics while running in an AFT shoe.

23 runners (11 women, 12 men) with an average age of 25.4 ± 2.7 years were recruited for the study. They ran randomly in 3 different types of running shoes, neutral, lightweight (responsive foam) and AFT at 3 self selected running speeds. A run at their 'training effort', a tempo run and at 5 km race pace.

Biomechanical variables associated with BSI such as cadence, vertical ground reaction forces, ankle and rearfoot eversion forces were measured during each run and shoe condition.

Results show that with neutral running shoes, ankle plantarflexion moment was higher compared to lightweight foam and AFT. There was less rearfoot eversion movement in the neutral shoe compared to lightweight foam and AFT. 

Cadence was lower while running in AFT shoes  compared to neutral or lightweight foam shoes. This is relevant since a longer running stride has been linked (in earlier studies) to BSI in the lower limbs.

Rearfoot eversion velocity (the speed at which your foot rolls down and inwards), or pronation was higher in the lightweight foam shoe compared with both neutral and AFT shoes. There was no significant difference in this between the neutral and AFT shoe.

The authors concluded that there were increases in several biomechanical variables associated with BSI  while running in AFT shoes. Although these changes were small, they tend to accumulate and can contribute to increased forces on bones in the lower limbs.  

The authors suggest that rotating running shoes and gradually using AFT to adapt to the differences may help reduce potential injury risk while optimizing running performance.

Reference

Bruneau MM, Gaudette LW, Sirls E et al (2026). Biomechanics Associated Withe Bone Stress Injuries While Using Advanced Footwear Technology In Elite Distance Runners. PM & R. 18(2): S143-150. DOI: 10.1002/pmrj.70153

Running Faster May Not Cause Shin Splints

Frequent site of shin pain/ stress fracture

We runners have always been told to train and don't strain. Running too fast, too often, can be a sure recipe for injury. That's why we always have an easy day for recovery after a hard session, to reduce our risk of injury. No runner wants to hear that they have a stress fracture or a small crack in their bones caused by overuse.

We think that when we run faster, we put more strain and load through our muscles and bones. So chances of a muscular or bone stress injury should be higher when we run faster.  We all assume that running slower (or slowly) causes less strain on our legs than running fast.

According to newly published research, fast paced running does not put any more pressure on your tibial (shin bone) which is a common area for shin splints and stress fractures than slow easy runs.

Runners in that study were asked to run at their own selected pace of slow, moderate and fast (but not all out). Reflective sensors were attached to their hips, knees and feet while they ran over force plates that measured impact (load) with each step.

I was really surprised to read that the slow paced runs (and not the fast runs) resulted in the most strain. Running at 'normal' or moderate pace for these runners caused less cumulative load than running the same distance at fast and slower speed.

The authors concluded that running fast does not necessarily cause more load on your tibial (shin bone) than slow running. Well, no excuse not run intervals once a week then if you're training for a race.

However, it may be too early to use this information to change our training habits as fatigue definitely does affect load when we run. Personally, I do feel I need an easy day of training to recover after a hard bike, run or weights session. Even when I was competing, it's usually 2 hard days of training back to back with a easy day (or total rest day) after. That way you won't have to worry about getting injured. Until an an accident strikes ......

Reference

Hunter J, Garcia GK, Shim JK et al (2019). Fast Running Does Not Contribute More Cumulative Load Than Slow Running. Med Sci Sp Ex. 51(6): 1178-1185. DOI: 10.1249/MSS.0000000000001888

What My Patient Has In Common With Soldiers

 

Picture from statpearls.com

I wrote last week that Byron had an interesting case. A patient with a foot condition that the doctor may have missed. This patient started having dull, aching foot pain 6 weeks ago after a game of tennis.

He had been playing tennis more frequently at a higher intensity, besides running and cycling. Since the pain started, he had stopped all exercise. He consulted a doctor a month ago and was diagnosed with 'inflammation in the tendon of the 2nd toe'.

Upon assessment, the patient could perform all functional tests like heel raises, toe raises and single leg hops with no pain. There was just a slight difference in muscle strength in the patient's painful foot. No pain at all during muscle strength testing, which is common during tendon injuries.

Picture from Merck manuals

The patient's pain was immediately reproduced upon specific palpation of his 2nd toe, along the shaft of the metatarsal, suggesting that he had an almost recovered "March" fracture.

March fractures (or metatarsal stress fractures) were first described in literature in 1855 in Prussian soldiers after they experienced pain and swelling in their feet after long marches. They are usually caused by repetitive stress and extrinsic environmental risk factors. If a patient is nutritionally deficient in Vitamin D or calcium, the risk of these fractures occurring are increased.

March fractures occur most commonly in the second or third metatarsals when they are unable to withstand the load from excessive forces/ loads. The second toe is less flexible and is prone to more torsional forces due to its attachments to the cuneiform bones.

Diagnosis is based on physical examination followed by confirmation by x-ray imaging.

We did not suggest that the patient go for an x-ray since it's been 6 weeks since the pain first occurred (stress fractures take approximately 6 weeks to heal). We advised him to gradually resume his exercise routine after treating him.

Reference

Warden SL, WB Edwards and RW Willy (2021). Optimal Loading For Managing Low-risk Tibial And Metatarsal Bone Stress Injuries in Runners: The Science Behind Clinical Reasoning. JOSPT. 51(7): 322-330. DOI: 10.2519/jospt.2021.9982