Extending Bottom Time
by David Hochman
Comfortably extending bottom time is something spearfisherman strive to achieve to be more efficient hunters. To do this we must increase our breath hold time through practice, training and breathing techniques. This allows us to be more efficient on the bottom while hunting, and achieve greater depths. However, long breath holds do not come without risk of death. As our bottom time increases, so does the risk of shallow water black out leading to death. Hyperventilation which most freediver’s practice to increase their breath hold time, is a known cause of shallow water blackout. The primary drive to breath is increased carbon dioxide (CO2) levels. When we hyperventilate we “blow off” and decrease our blood CO2 levels, thus, decreasing our desire to breath and increasing our breath hold time. So, the more we hyperventilate, the longer we can hold our breath. This leads to our oxygen blood levels (PO2) to decrease which leads to black out. There is a safe balance, and achieving that balance is necessary for free divers or catastrophe will occur. You must always keep safety in mind, and never take risks. Please read my page “avoiding shallow water black out” I recommend you follow these basic rules.
There are many ways to increase bottom time, here are eight techniques I use successfully:
1. Relaxation– You must be in and maintain a relaxed state throughout your dive. A heart rate below 45 bpm is ideal. Methods of meditation will help you achieve this goal. Self-taught meditation is achievable and the state you are looking for is best described as follows. We have all been in this state in the comforts of our homes, the trick is getting there in the water. It is the moment before we fall asleep. It is the moment in time when we are in a semiconscious state, yet aware of our surroundings. That moment of complete comfort and relaxation. As freedivers this is the state we strive to be in during our dives.
2. Efficient movement – All movement underwater must be thought out and used only if it is efficient and necessary. For example your legs are large muscle that consumes a lot of oxygen (O2). To be more efficient, walk on the ocean floor with your fingers rather than kicking your legs. On your way down to the bottom, make an efficient pike then kick your fins with long, slow, efficient strokes. When you are down approximately 30 feet, stop kicking and maintain your body so it is hydrodynamic. Then coast to the bottom effortlessly, conserving energy. On your return make long, slow, efficient kicks maintaining a hydrodynamic body posture and stop kicking 15 to 20 feet from the surface, relaxing, as your body continues an upward motion until you pierce the surface.
3. Properly Ventilate– We as freedivers must breathe more efficiently than most. Belly breathing at a slow methodical rate is the most efficient method of ventilation. We must master this method of breathing to achieve efficient exchange of gases in our system and efficient respiration.
4. Rest between Dives– When diving, it is critical that you allow yourself adequate time to recover between each dive. It is crucial that you live by the following recovery ratios ; 2: 1 when depth is < ~60 feet and 3 : 1 when depth is > ~60 feet (or when breath holds are >~90 seconds). It is best to never go over 90 seconds for safety purposes. An example of this rule during a dive would be as follows; If the diver is in less than 60 feet, and have a 1 minute dive the diver would then take 2 minutes on the surface to recover. Hence, the 2:1 rule. (It is critical to have a freediving watch to keep track of bottom and surface times. I personally use the Mares Smart Apnea).
5. Hyperventilation– Freediver’s hyperventilate to increase their bottom time, however, over ventilating is dangerous and will lead to blackout. A safe rule to avoid excessive hyperventilating is limiting deep breaths to a maximum of 3 hyperventilation breaths immediately before the dive.
6. Increase vital capacity – With proper training and in short order, we can increase our lungs carrying capacity by 3 liters or more. This is an enormous amount of extra oxygen we can carry during our dive. This is best achieved through the following techniques.
a) Standard Air Packing- After taking a full breath, filling our lungs as much as possible we then suck air into our mouth by lowering our gullet/tongue and siphoning air in though pursed lips. This is the same as when you would suck up water through a straw but in this case it is air going into our oral cavity, and down the lungs. when you cant hold anymore air in your lungs gulp air into your mouth. Next seal your lips trapping the air in your oral cavity. Now raise your tongue, progressively flattening it along the palate, starting at the tip and moving backwards. The tongue is now working like a piston, compressing the air and forcing it down the trachea, past a now opened epiglottis and into the lungs. This is repeated until the lungs are packed full of air. When the mouthful of air is ”packed” into the lungs, the epiglottis can be locked holding the air in the lungs for 20 to 30 seconds and then the process repeated.
b) Hochman’s Air Packing Technique: Take a full breath filling your lungs , hold it for 20 seconds (this 20 seconds will allow the lungs to stretch) then take another breath smaller but filling your lungs fully. You will be “stacking” these breaths one on top of the other in your lungs. Repeat this for 1 to 2 minutes until the lungs are packed full of air and hold your breath with full lungs for 30 seconds. Exhale and repeat.
c) Mechanical device- There are several mechanical devices on the market that cause resistance and work well. A simple but effective method is to strengthen your breathing by breathing through a straw or air restricting devices like a 4 ft piece of garden hose. This method will stretch and strengthen the intercostal muscles. In addition, breathing through an air restricting device will limit the amount of carbon dioxide that is expelled with each breath and build up the body’s tolerance to increased concentrations of carbon dioxide causing hypercapnia.
7. Reduce sensitivity to high carbon dioxide and low oxygen– The primary drive to breath is from elevated C02 levels or hypercapnia. The state of the body being hypercapnic (high Co2 levels) is the driving force to breath. This is what creates the scream in our heads to take a breath. We can overcome this drive with techniques that put us in a hypercapnic state. This is best achieved, when done on a daily basis. The following exorcises will help you do just that.
1. Deep breathing =1 min ànd hold for a 20 sec breath hold
“ “ = 1 min ànd hold for a 30 sec “ “
“ “ = 1 min ànd hold for a 45sec “ “
“ “ = 1 min ànd hold for a 60 sec “ “
Repeat the above back to back. Repeat until breath hold is between 2 and 3 minutes or until your nail beds turn bright red (this is due to hypercapnia).
2. Apnea walk/run. Course=Mark 25 ft., 50 ft., 75 ft., and 100 ft. Hyperventilate then take a deep breath and hold, next walk or run different distances on the marked course repeatedly. This will also help you with a visualization of these distances when diving depths.
3.Apnea pushups= Lay on your back and pump up, Hold your breath for 1 minute then roll over and do as many pushups as possible while breath holding. Repeat.
4. Machine training during breath holding. This is as it sounds, and can be done with any strengthening machine (pecks, bicep, tricep, legs and back machines). Take caution as you can pass out.
8. Improve pulmonary efficiency– This is best achieved by doing a daily cardiovascular workout such as running or bike riding. As a general rule you want to get a sustained peak cardiac output for 20-30 minutes.
**All of the above training methods increase the risk black out, so please attempt only where a soft fall is possible. Do not do them in or around water. You must clear yourself of all and any medical conditions prior to doing these training methods.