Amateur runners: hop or hope for better performance?

Improving muscle economy

Research shows that running economy is strongly linked to stiffness and elasticity connective tissues in the body, particularly tendon tissue⁽⁸⁾. In particular, tendons in runners that are stiff and springy are more able to store energy during footstrike and return this energy to the runner as he/she pushes off for the next stride⁽⁹⁾.

In particular, the evidence suggests that the Achilles tendon plays a particularly significant role in running economy⁽¹⁰⁾. Studies on the anatomical characteristics of Kenyan and Japanese elite distance runners found that the Kenyans’ superior running performance was directly related to higher relative tendon lengths and greater tendon force return capacity⁽¹¹⁾.

It follows therefore that if tendon length, stiffness and ‘springiness’ can be increased, running economy (or muscle economy for sports in general) will be improved. The question is, can tendons be ‘trained’ to improve these qualities, thereby giving the athlete an uplift in muscle economy and endurance performance?

Training options

The good news is that in recent years, a solid base of evidence has accrued showing that muscle economy can indeed be trained. In particular, the use of resistance training, plyometrics training and stretching, have all been shown to induce the metabolic, biomechanical and neuromuscular efficiency changes needed to enhance muscle economy in endurance athletes such as runners and cyclists⁽¹²⁾. These changes involve increasing the stiffness of muscle/tendon units, which increases the storage and release of kinetic energy during steady-state rhythmic activities such as running, swimming and cycling.

Although activities such as resistance training and stretching can help improve running economy, one criticism of them is that for endurance athletes, replacing too much endurance training time with resistance or stretching work could be a double-edged sword; although muscle economy and efficiency might improve, this benefit could be outweighed by lower aerobic endurance gains as a result of reduced aerobic training volumes.

Instead, some researchers have proposed that a more promising approach to maximize running performance could be to supplement endurance training routines with additional training strategies that more closely mimic the activity of running (for more running specificity), and which also improve muscle/tendon stiffness while simultaneously taxing the aerobic system. As such, it has been suggested that plyometrics training consisting of repeated jumps, hops, or sprints could be a more appropriate to train muscle economy.

Another benefit of this approach concerns the development of tendon bulk and stiffness; research shows that collagen production in tendons (paramount for tendon stiffness) is most effectively triggered by intermittent, progressive-loading programs with relatively short durations and intervals⁽¹³⁾. By performing this type of training as part of a running program therefore, athletes could potentially see the greatest gains in muscle economy without a restriction in endurance-specific training.

New research

To test this theory, a team of German scientists have investigated the effects of a daily plyometrics hopping intervention on running economy in amateur runners⁽¹⁴⁾. Published earlier this month in the journal ‘Scientific Reports’, this study compared ‘running-only training’ to ‘running plus daily hopping plyometrics’ in thirty-four amateur runners. Importantly, since most of the available evidence on exercise interventions to improve running economy has previously focused on athletes with moderate to high-performance levels, the researchers looked only at recreational and amateur runners. This was to assess how effective (or otherwise) such an intervention could be for non-elite runners – ie the vast majority of runners out there pounding the streets!

What they did

Thirty four active amateur runners were recruited from local running clubs in the area. To ensure the required fitness levels (ie that the participants were able to complete the running protocol), individuals had to be have 10km times of 55 minutes or less, be younger than 40 and have no health or injury problems. The runners were then randomly assigned to either a control or hopping group. Both continued with running training, but while the control group did not engage in any additional specific exercise intervention, the hopping group also completed a six-week plyometrics hopping protocol.

Each day, the runners in the hopping group performed a variable amount of double-legged 10-second hopping bouts (see table 1). While total session duration (5 minutes) was constant, the number of sets (and with this, active training time within that 5-minute window) was increased weekly in order to ensure safe functional and mechanical adaptation. During the 6-week intervention, all participants completed a training diary, documenting their weekly running activity (number of sessions, hours per session, pace) as well as other any other exercises in hours per week, and for the hopping group, their adherence to the hopping intervention.

Table 1: Protocol of the hopping intervention

Before and after the 6-week intervention, each runner was tested for running economy by measuring submaximal oxygen uptake (VO2) during 4-minute stages at three constant running speeds on the flat. After a standardized warm-up of 3 minutes of walking at 5kmh, the participants ran at 10, 12, and 14kmh, respectively during which economy was measured. Peak oxygen uptake (VO2peak) was also determined two minutes after runners had completed the last submaximal running stage at 14kmh. The results from the two groups were then compared.

What they found

The key finding was that six weeks of daily hopping exercise significantly improved running economy at the two higher running speeds (12 and 14kmh) in these amateur runners (see figure 2). There was also a trend towards improved running economy at 10kmh, but it was not quite large enough of a difference for the scientists to be confident it was statistically significant. The second finding was that the runners who completed the hopping protocol showed no losses in aerobic capacity (oxygen uptake) compared to the control group. This indicated that there was no negative impact of adding the hopping training to the running program.

Figure 2: Running economy with and without hopping training

Blue circles = average oxygen consumption per minute per kilo of bodyweight in the hopping trained runners. Orange circles = average oxygen consumption for the control group runners. Vertical bars show the degree of spread of results within the group. The lower oxygen consumption in the hopping training runners (blue circles) indicates that less oxygen was required to maintain that pace, which means better running economy. Although also trending better at 10kmh in the hopping group, the difference was not quite large enough to be considered statistically significant (a repeat study with a larger group of runners would probably show significance) .

Implications for runners

These findings that plyometrics-type hopping exercises can improve running economy in amateur athletes are in line with those of another study conducted way back in 2003⁽¹⁵⁾. However, what’s really fascinating compared to the previous research is that in this study, the plyometrics exercises consisted of just five minutes per day of one simple and easy-to-learn hopping exercise. In contrast, the earlier studies used three weekly sessions with durations of up to 30 minutes as well as multiple jump exercises. Not only are these longer interventions more onerous to stick to, they also require more skill and practice, and also often need additional equipment (eg benches for drop jumps).

Overall, the take-home message is that daily plyometrics in the form of short bursts of hopping can be easily and safely implemented (none of the hopping trained runners reported any adverse effects or injuries) within a running program, leading to good improvements in running economy. This study also shows that economy gains are not just for high-level and elite runners - amateur and recreational runners can make significant gains too. Given that this intervention takes up very little time and effort, it’s therefore a no brainer for any runner seeking improvements in efficiency. To try it for yourself; to ensure a safe and progressive build up, simply try the protocol in table 1. Don’t hope for better performance – hop for it!

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