Quick summary

Zlagboard Forearm Endurance Workout

The Zlagboard comes with a built-in protocol for forearm endurance training, developed by Duncan Brown, an Australian climber and coach [1][2]. The idea behind the Zlagboard Forearm Endurance Workout is to generate a severe forearm pump, targeting the anaerobic lactic energy system. This allows you to train both physiological tolerance and psychological tolerance to high acidic loads [3]. The Zlagboard Forearm Endurance Workout could perhaps be viewed as a rather extreme version of Hangboard Repeaters, or Eva Lopez SubHangs protocol, where the hang time and the rest times are one minute each [4][5].

Zlagboard Forearm Endurance Workout details

  1. Mount the hangboard and support your feet on a chair, or some screw-ons on the wall.
  2. Choose a pair of holds, e.g., 20 mm edges, and hold it for 1 minute.
  3. Dismount the hangboard and shakeout for 1 minute.
  4. Perform ten sets.

Table 1: Zlagboard Forearm Endurance Workout summary.

Zlagboard Endurance
Approx. BM load30 - 70%
Hang time [s]60
Rest betw. sets [s]60
TUT [s]600
Total time [min]19

Zlagboard Forearm Endurance Workout remarks

  • To prevent blood from flooding your forearms directly after dismounting the hangboard, hold them up for a couple of seconds, and shake out.
  • You may apply the above strategy after finishing a pumpy route – holding your hands up will help you regenerate faster before your next burn.
  • You can increase the level of intensity of the exercise by squeezing and releasing your fists in the upright position throughout the 1 minute of rest.

Muscle endurance and fatigue mechanisms

Muscular endurance in itself is a complex subject, and forearm endurance in climbing is no exception. In general, endurance can be defined as the ability to maintain or to repeat a given force or power output, which perfectly describes the periods of intermittent contractions mixed with periods of sustained contractions of the finger flexors, characteristic for climbing on a sport route [6][7][8]. Currently, the physiological mechanisms that allow elite level climbers to maintain repeated intense isometric contractions for prolonged periods of time are not fully understood, but there is evidence that flexor muscle oxidative capacity, capillarity, and ability to profuse O2 may be the governing factors. For one thing, it was discovered that high-level climbers are able to de-oxygenate the flexor muscles to a greater extent than intermediate climbers and non-climbers during sustained contractions. What is more, the flexor digitorum profundus (FDP) oxygenation recovery is significantly quicker in elite climbers during both sustained and intermittent contractions, while it is known that enhanced O2 delivery to the exercising muscles directly attenuates muscle fatigue and increases muscle efficiency [9][10][11]

Since blood flow brings oxygen necessary for aerobic adenosine triphosphate (ATP) production and removes by-products of metabolic processes in working muscles, it plays an important role in the maintenance of force output.  As the muscles contract, the mean arterial blood pressure increases, leading to a decrease in the net blood flow to the working muscle and inducing fatigue. Surprisingly, blood flow occlusion does not seem to be the critical factor in the development of fatigue, as the decrease in the MVC force was found to precede significant changes in the blood flow to the muscle [10][12].

ATP is the energy source fuelling muscle contractions, and glycogen oxidation is the primary source for ATP regeneration during high-intensity intermittent exercise [13]. Glycolysis leads to blood lactate (Lac) and hydrogen ions (H+) accumulation, which until recently was thought to play a vital role in the development of muscle fatigue. This view is now being challenged, as several recent studies have shown that decreased pH may have little effect on contraction and MVC of human muscle [10][14].

Anaerobic metabolism in skeletal muscle also involves hydrolysis of phosphocreatine (PCr) to creatine and inorganic phosphate (Pi). The concentration of Pi increases rapidly during intense contractions, which appears to be the most important cause of fatigue. It is hypothesized that elevated levels Pi can lead to decreased force production by limiting Ca2 release from the sarcoplasm (SR) [14][15]. Finally, mitochondrial respiration produces ATP and consumes O2 in a process that generates reactive oxygen species (ROS) that are known to contribute to muscular fatigue [10].

Zlagboard Forearm Endurance Workout hang intensity determination

So what does happen when the Forearm Endurance Workout is being executed? Let’s first take a look at the hang intensity. Based on a simple analysis of the mechanical system involved and some very rough measurements, we can state that the hang load lies in the range between 30% – 70% of the climber’s body mass (BM), depending on the type and position of the feet support used [16]. This result can be confirmed through a simple experiment, as it is shown in Figure 1. In terms of the %MVC, this could mean anything, but if we choose a reasonably comfortable hold, on which the training climber’s MVC is around 150% BM, then the hang intensity should lie somewhere in the range