Dietmar Schmidtbleicher on Interference Effects of Concurrent Training

Strength and power expert, Prof Dr.Dr. Dietmar Schmidtbleicher has been invited for a 2-hour discussion regarding sports conditioning-related topics with a small group of strength and conditioning coaches in January 2016.

For a record, the German scientist has published ~480 scientific journals and articles since the late 1970s when he started with his research studies. One of the topics we discussed was interference effects of concurrent training.

Schmidtbleicher during NSCA conference in Orlando

Concurrent training is a structure of training combining endurance (aerobic) and strength training during a single training session. This structure is usually applied by coaches to reduce the number of training sessions that the athletes have to do in a week, as well as to obtain a certain mileage goal of running endurance for a particular week.

Hence, they have athletes to perform aerobic endurance first and then followed by strength session with the conditioning coach. Despite these reasons, the structure may not be the best training arrangement according to Schmidtbleicher.

One example of arrangement that has been used by coaches is to have athletes to perform endurance training such as long slow distance for 10km, and followed by weight training (e.g. 3 sets x 10 reps bench press) after some period of recovery (~20 mins).

The first point that highlighted by Schmidtbleicher sounds like this, “neuromuscular condition is good if you’re not fatigue”. The neuromuscular system is certainly at best for performing many athletic movements during "fresh" condition.

In contrary, it can be a problem for athletes to execute a sound technique of strength exercises when they are in a state of fatigue. Thus, Schmidtbeicher suggests the athletes perform running endurance and strength training, not at the same session.

by Hawley (2009), A Physiol Nutr Metab

One reason for "splitting" the two types of training can be justified when we look at the “interference theory” which explains the “competing effects” occur at cellular level associated with performance of aerobic endurance and strength training simultaneously at the same session.

The activation of enzymes (i.e. AMPK) important for the process of energy production (i.e. mitochondrial production) in aerobic endurance are not compatible, and in fact can possibly impedes the enzymes (mTORC1) that should be activated during strength training to regulate the protein synthesis (for cell growth).

This “blocking” of the signaling pathways could minimize the adaptation of training. Threfore, athletes may not get an optimal benefit during concurrent training that is structured as above.

Moreover, long-term performance of high volume or intensity of concurrent training may promote overreaching (while getting minimal training gain), which can possibly put athletes into the state of overtraining.

Nevertheless, it is still important to scrutinize or make an in-depth inspection on this topic. We may want to look further at the dose-response relationship, specific objective (body composition et.?), type of endurance training (running, walking, cycling, swimming?), type of strength training (hypertrophy, strength, power), training structure for optimal training adaptation (lesser interference effect) while maintaining sports-specific requirement (for endurance-strength sports), and current research looking at these variables on the magnitude of interference effects from concurrent training. This allows one to ascertain if the aerobic endurance and strength training can be performed together at some degrees.

From existing information (e.g. Wilson et al., 2012, JSCR), what we already know is that concurrent training can affect power production. If one has to do concurrent training, he/she must choose endurance modality that specific to his/her sports in order to avoid the occurrence of competing adaptations. For sports requiring strength and power, it is suggested to perform endurance activity at a higher intensity (e.g. 10 x 100m @ ~70%), rather than the 20-40 mins of a slow jog.

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Whole Body Vibration for Sports Performance - Does it Works?

Russian scientists have examined the application of "vibration" for performances, such as strength and power quality. It dates back to 1970's and more research on vibration were published subsequently in 1980's and 1990's such as those of Nazarov and Spivak (1987), Issurin (1994, 1997 etc.), Bosco (1998 etc). Issurin's 1994 work was the first study of vibration in athletic performance (strength, power, and flexibility) that was published in English. Unlike the current practice, he actually used vibration to specific parts of the body.

Most of the studies that were published after 2000 reported positive benefits following vibration exposure (e.g. using the Whole Body Vibration, WBV). However, WBV is not invariably favorable and appears to depend on fitness level and the WBV variables (will be discussed).

Recreational / untrained subjects
There appear to be some benefits of WBV to this group. Most probably they are more responsive to the intensity of WBV, which resulted in an increased muscle activation. In the last 10 years, enhancement of jump performance, sprint ability, change of direction, flexibility, and balance have been reported following exposure of WBV.

Elite athletes
The effect of WBV on elite athletes is not conclusive. The most frequently cited reasons for the insignificant results following exposure of WBV is "insufficient stimulus" and "dampening effect." The stimulus of WBV comes from one or more of the WBV variables such as intensity, duration etc. (will be discussed). Dampening effect is associated with internal and external factors. The internal factor related to athlete's fitness level, basically, the fitter you're the more stimulus is needed. The external factor may be related to an accessory that can possibly weaken the vibration signals such as your shoes.

Application of Whole Body Vibration.
There are a few variables to consider, primarily the amplitude, frequency, volume, and recovery.

• Amplitude - as determined by displacement (peak to peak distance, in mm) of the wave-like shape (sinusoidal) that is produced by vibration device. The amplitude can determine the "up and down" of movement.
• Frequency - number or rate of the wave produced in a minute. In layman's, given 50 Hz vs 40 Hz of frequency, 50 Hz vibration can "shake you" a bit more than the 40 Hz. 
• Volume - this is the duration of exercise. In literature, 30s of WBV with an appropriate set of amplitude and frequency can elevate performance (e.g. jumps). Most of the studies used 30s to 2 minutes of total duration for warm up application, and this can be longer when WBV applied as training mean.
• Recovery - rest between WBV exposure (e.g. set 1, set 2 and so on) and also recovery between last WBV to the performance. Rest between exposure is around 1:1 work to rest ration and the recovery before performance is at least 1 minute.

The physiology of vibration

Vibration can produce wave and energy. During the WBV exposure, the body is "accelerated" or "shaken" because of the amplitude and frequency of vibration. This will give a stimulus primarily from the activation of receptors, the muscle spindles. Activation of muscle spindles enabled reflex potentiation or a better recruitment of motor units. This effect can also be seen in other athletic activities such as plyometrics, dynamic warm up, and so on. The enhancement of neuromuscular recruitment results in improvement of neuromuscular excitability that is crucial for athletic performance.

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