A 2018 study looked at how various forms of cross-training affected runners' efficiency and vulnerability to injury. Before and after training with various cross-training modalities, the quality of high school runners' movements, running efficiencies, injury risk factors, and hip muscle strength were compared. 

Participants in the study swapped out two of their weekly easy runs for four weeks of cross-training. Those who wanted to run were split into three categories: cycling, indoor elliptical, and outdoor elliptical bike (the outdoor version of an Elliptigo). 

The study indicated that elliptical bike training was the only modality to enhance functional movement screen scores and running economy both before and after training. The 3,000-meter times of all groups increased, although the benefits were statistically significant only for the cycle and elliptical bike groups. This highlights that these may be the most beneficial cross-training modalities to include in early-season training to improve running performance.

Competitors at the elite level. As we get older, we have to think more about the time it takes to recover from higher intensity and higher volume labor, or else the danger of damage will outweigh any benefits. After a day of speedwork or a long run, incorporating a day of active recovery on the elliptical bike, indoor elliptical, or cycle can help flush out the legs without adding undue impact and stress to the body. Two sessions of light cross-training could replace simple recovery runs, providing the same fitness stimulus with less chance of running-related injury.

Teenage athletes, especially during the off-season. Injury, emotional exhaustion, and even eating disorders have all been linked to the premature specialization of young athletes. Cross-training, at no more than 45 to 60 minutes at a time, on two days per week instead of two days of easy running can help prevent overuse injuries and help the adolescent athlete gain confidence before the start of the track or cross-country season, just as it does for masters athletes. A study from 2023 indicated that adolescent long-distance runners evaluated a lack of cross-training before their season as significantly contributing to running-related ailments. 

Athletes aiming to enhance their turnover but who cannot stomach an additional day of running speedwork. Cross-training can simulate the increased turnover and reinforcement of certain movement patterns, but specificity will always be the winner. Depending on the needs of the athlete, there are a variety of possible formats for this. Similar to how an easy run with flat or hill strides would be planned, a 45- to 70-minute cross-training program could conclude with intervals of 20- to 30-second strides followed by 30- to 60-seconds of easy recovery. 

Extrapolating from these workouts, you can do longer intervals of 5k-10k effort with equal 1min easy recoveries (10-15 1min intervals) or longer threshold efforts of 5x5min with 60-90s easy recoveries (5 rounds of 5min). To achieve the same heart rate for equal running efforts, I suggest arranging these types of sessions on an elliptical bike, indoor elliptical, or cycle, and keeping an eye on heart rate for the intervals.

Athletes that have lost interest in running due to overexposure. It's not uncommon for athletes to grow tired of their favorite activity after putting in countless miles and constantly changing training regimens. This undesirable holding pattern is typically maintained by these athletes due to the fear of fitness loss associated with not running. 

Cross-training, in which the athlete engages in activities other than running, can help alleviate this anxiety, reduce the risk of running-related injury, and keep the athlete feeling like an athlete. Keep their workouts light and aerobic for the first two weeks, and then gradually introduce interval-style activity to keep them motivated and feeling good. 

To avoid being overly focused on the forms of cross-training that are most running-specific or provide the greatest fitness gains is arguably even more crucial for this category of athletes. Instead, pick something that really appeals to your sense of adventure and enjoyment to help you return to viewing exercise in a playful light.

Athletes with injuries are the most common group to use cross-training. It's never fun to be hurt, but knowing that aerobic fitness, maximal oxygen consumption, and running economy can all be maintained and improved through cross-training should bring some solace to injured athletes. The most important takeaway here is that if you are an injured athlete, you do not necessarily have to try to log the same number of training hours that you did while running, particularly if you were routinely clocking two to three hours or more for your long runs.

 Aim for four to five days of constant, easy effort per week, and two days of interval training, wherein one session each week includes longer threshold work and the other session is shorter, higher intensity activity. You should find a happy medium between letting your body rest and recuperate and pushing it too hard in your cross-training sessions, taking into account the severity of your ailment and the advice of your medical professionals.

Numerous athletes choose not to cross-train.  For certain runners, not only those forced to cross-train due to injury, it's a terrific option. This idea needs improvement to determine if cross-training is best for an athlete. It can be beneficial when balanced properly and intentionally in a well-rounded training program, as seen above.  Cross-training can add variety and reduce running-related injuries, but most importantly, fitness must be pleasant.