RESEARCH: Studies shared from 6 to 12 Feb 23

All the studies I've shared are available on the RESOURCES PAGE.

This week's quick summary:

• Racing shoes (Vaporfly) for running economy at slower speeds
• Self-directed strength training to reduce running injuries
• Autonomic recovery after exercise in trained athletes
• Effects of the Nike Vaporfly on long-interval training performance
• 18-week general strength and foam rolling for injury prevention

EQUIPMENT: Effects of highly cushioned and resilient racing shoes on running economy at slower running speeds

Supershoes provide a benefit at high speeds (and also on moderate uphill and downhill courses too). However, it is not clear whether these benefits are also available at slower speeds. This study set out to test the Nike ZoomX Vaporfly Next% 2 at slower speeds.

STUDY DETAILS

1. The Nike Vaporfly line of running shoes improves running economy by ∼2.7% to 4.2% at running speeds of 13 to 18 km·h−1.
2. Our purpose was to determine the effects of the Nike ZoomX Vaporfly Next% 2 (VFN2) on running economy at 10 and 12 km·h−1 compared with a mass-matched control (CTRL) shoe.
3. Sixteen runners completed 4 × 5-minute trials at both 10 and 12 km·h−1 on the same day.
4. A 2-way repeated-measures analysis of variance showed a significant shoe × speed interaction for oxygen consumption.
5. At 12 km·h−1, oxygen consumption was lower for VFN2 relative to CTRL.
6. From these data, it appears that the VFN2 still enhances running economy at 10 and 12 km·h−1.

PRACTICAL TAKEAWAY

There are performance benefits from using supershoes at slower paces. Not all supershoes are the same (here is a previous study comparing seven carbon-plated shoes) and there are differences in the fit and comfort depending on a runner's foot shape. This means it is important test and try different options. Overall, my recommendation is for any runner who wants to perform their best in road running races to find the most comfortable supershoe for them.

STRENGTH: A randomized study of a strength training program to prevent injuries in runners of the New York City marathon

I have shared many studies investigating the benefit of strength training for running economy and performance (search for "strength" on the resources page). There appears to be a performance benefit for specific strength training protocols for runners (heavy lifting and plyometrics). However, many athletes consider strength training as a means of injury prevention which is what this paper set out to test.

STUDY DETAILS

1. Twelve weeks before the New York City Marathon, first-time marathon runners age 18 years and older were randomized into a strength training group or an observation group.
2. The strength training group was instructed to perform a 10-minute program 3 times weekly using written and video instruction.
3. A total of 720 runners were enrolled, of whom 583 runners started the marathon and 579 completed it.
4. The incidence of major injury was 8.9% and minor injury was 48.5%.
5. The incidence of overuse injury resulting in marathon noncompletion was 7.1% in the strength training group and 7.3% in the observation group.
6. There is a high prevalence of injury among first-time marathon runners, but this self-directed strength training program did not decrease overuse injury incidence resulting in marathon noncompletion.

PRACTICAL TAKEAWAY

A self-directed strength training plan of three, 10-minute sessions per week did not appear to have any injury reduction effect. This suggests that short, self-directed strength training may not be enough to reduce injuries.

The good news is that a more thorough and complete strength training session may be beneficial. See the final study in today's newsletter.

PHYSIOLOGY: Autonomic recovery after exercise in trained athletes

STUDY DETAILS

1. Nine highly trained (HT) male runners and eight trained (T) male subjects completed preliminary testing to determine ventilatory thresholds (VT1, VT2) and VO2max.
2. HT performed four intensity-controlled training sessions: 60 min and 120 min below VT1; 60 min with 30 min between VT1 and VT2 (threshold); and 60 min above VT2 (6 x 3 min at 96% VO2max, 2 min of recovery).
3. T also completed the interval session to compare ANS recovery between HT and T.
4. Supine heart rate variability (HRV) was quantified at regular intervals through 4 h of recovery.
5. When HT ran 60 or 120 min below VT1, HRV returned to pretraining values within 5-10 min.
6. However, training at threshold or above VT2 induced a significant, but essentially identical, delay of HRV recovery (return to baseline by approximately 30 min).
7. In T, HRV recovery was significantly slower, with HRV returning to baseline by >90 min after the same interval session.
8. Further, the first ventilatory threshold may demarcate a "binary" threshold for ANS/HRV recovery in highly trained athletes, because further delays in HRV recovery with even higher training intensities were not observed.

PRACTICAL TAKEAWAY

I think this is a fascinating protocol and a useful means of testing whether or not a training session is easy enough when aiming to train below the first threshold. Intensity control is vital for managing training load and ensuring sustainable training so having another useful tool to help calibrate and learn the right intensity is very useful.

Marco wrote a detailed post explaing exactly how to do this. It is available here.

EQUIPMENT: Effects of the Nike ZoomX Vaporfly Next% 2 shoe on long-interval training performance, kinematics, neuromuscular parameters, running power and fatigue

STUDY DETAILS

1. Twelve well-trained men performed two long-interval training sessions (5 × 1000 m with 90s recovery period) 7 days apart, with the VPF shoe or a traditional running shoe (CON) in random order.
2. Long-interval training performance improved 2.4% using the VPF shoe compared to CON.
3. Step length, contact time and leg stiffness were higher while flight time was lower when using VPF.
4. Running power decreased in a similar way in both conditions throughout the training session.
5. Vertical power was significantly higher in the VPF condition.
6. Finally, the perceived muscle pain was influenced by the shoe model condition
7. VPF shoes improved the long-interval training performance with similar running power, heart rate and neuromuscular fatigue, and reduced subjective perceived muscle pain compared to regular training shoes.

PRACTICAL TAKEAWAY

The Vaporfly is a fantastic shoe and this shows in the improved performance in interval training. I believe all of these results (see the study above too) provide evidence that it is a necessity to have a pair of these shoes in your shoe rotation.

There was some interesting discussion when I shared this on Twitter. A great question asked "Would we be better running in the traditional shoe and doing less for the same stimulus?" and one of the study authors replied "We believe this shoe allows for more training volume on high intensity days, and volume is key in improving performance". This suggests that we're still not sure when best to use these shoes in training, but they are critical for race day performance.

STRENGTH: Effectiveness of an 18-week general strength and foam-rolling intervention on running-related injuries in recreational runners

STUDY DETAILS

1. To evaluate effectiveness of an 18-week general strength and foam-rolling intervention on the incidence of running-related injuries.
2. A total of 433 recreational runners participated (n = 203 female).
3. The intervention group (n = 228) performed general strength and foam-rolling exercises twice weekly for 18 weeks, the control group (n = 205) maintained their regular training habits.
4. Secondary analyses were performed on the subgroups of the intervention group based on compliance; low compliance (n = 100), intermediate compliance (n = 63), and high compliance (n = 65).
5. The cumulative incidence proportion for the control and intervention groups was 27.1% and 23.0%, respectively.
6. A significant difference existed between the high-compliance subgroup and the control group.
7. Recreational runners highly compliant with the intervention were 85% less likely and took on average 57 days longer to sustain a running-related injury when compared with controls.

PRACTICAL TAKEAWAY

In contrast to the first study in this newsletter, this one showed that there may be a decrease in incidence of injuries when performing strength training and foam rolling. I believe that the key difference was that this intervention was more thorough and that the population where the benefit was seen was in the high-compliance group. Strength training therefore needs to be done consistently and thoughtfully to achieve the desired injury mitigation benefits.

The effective strength training plan was a 30 minute routine of "strength exercises for the abductors, quadriceps and foot supinators including 1-leg squat, forward lunges, side-steps with elastic training band, supine abduction with elastic training band, side-plank, diagonal lifts and foot supination with elastic training band (taking approximately 19 minutes to perform), and foam-rolling exercises for the upper leg; hamstring, quadriceps, gluteal and abductor muscles, and lower leg; plantar fascia, calf and shin muscles (taking approximately 11 minutes to perform)".