This exercise is a simple, fast way to get a good apnea workout, emphasizing CO2 training with a relative amount of safety since it is done entirely dry. For more advanced divers wishing to move the exercise more in the direction of low O2 and lactic tolerance, it can be done on an exhale or with extremely short rest/breathe periods. It's intended to be a low to moderate intensity apnea exercise, and should be challenging but NEVER DONE TO FAILURE (samba or blackout). CO2 headaches are common with this exercise. Please read the warnings at the bottom of this article; this is private training information and intended only for healthy individuals who have been cleared by a physician, and like most all of my training articles, is intended for divers who have been through one of my programs or equivalent.
This apnea bike exercise simulates breathing up and diving in a current by challenging the diver to maintain a steady state of exertion while performing breathholds on a regular timed interval, and it puts some load on the quadriceps which are a primary muscle for bi-fin kicking--this has the added advantage of training the muscle to recover more quickly from an apnea workload, and also provides a more effective boost in EPO levels than static tables. As presented here, it's particularly good for spearos or divers looking to increase stamina for repeat diving as well as build bottom time. I have used variations of this exercise for many years now.
Most beginner to intermediate divers, doing this 2-3 times a week, for 15-30 minutes a session, should be able to maintain dive fitness for surprisingly long periods when they can't get to the ocean. With consistent apnea bike plus ocean time and ideally some pool training, large gains in comfortable bottom time, depth, and stamina are possible. Nothing happens overnight, but most divers who stick with this see results within a month, and also make noticeable gains in static even without specifically training statics. Beginners training consistently will make the biggest gains, but shouldn't overdo it. The body needs recovery time, and training 2-3 times a week is plenty. Training load can be slowly increased but nearly always needs to be followed up with increased attention to diet and supplementation.
Competitive freedivers or spearos who practice deep aspetto may see more benefit in longer hold times and longer rest times since they will typically be training to do a fewer number of deeper/longer dives throughout a typical dive session. And for divers specializing in the no-fins discipline, an elliptical machine which also works the arms can be used instead of a bike.
I do this on a stationary bike, and I usually have a TV show playing on my phone to distract me. We need a way to measure our pulse, particularly when you are first starting out with this exercise. I particularly like wearing a pulse oximeter with this exercise.
1) First, figure out a target heart rate. For newer divers, 45% of max heart rate is a good start. For more advanced divers you can go closer to your max, but it should never be a sprint, you want to pick an aerobic pace that you could maintain for a couple hours if necessary. I feel like I get good results at about 65% of my max. This is based on what my heart rate is when kicking at the surface against a very brisk current. The generally accepted formula to determine 'max heart rate' is 220 minus your age.
This target heart rate is a baseline. When we actually do the exercise with apnea, it's normal for our HR to swing up and down. Typically it will drop during breathhold, particularly when contractions start, and it will spike soon after we start breathing again, then gradually come back down to our baseline.
2) We adjust the seat so our legs reach nearly full extension at the bottom of the pedal cycle. When we're kicking properly with long fins our knees should never bend more than 45 degrees, so we're going to pedal as close to this guideline as possible and work the quadriceps at full extension.
3) Start pedaling and aim for 65 rpm (this is faster than the pace of our kicks when actually diving. That's okay--train hard, dive easy). Now we check our pulse. We adjust the resistance of the bike so that we're hitting your target heart rate while maintaining a steady 65 rpm. For most of us, this will feel like a fairly easy pace. That's fine because at this point, we're still breathing! Make a note, we'll be keeping the bike at this resistance for at least a week or two. When I need a harder workout, I may increase the resistance, but I rarely pedal faster 70 rpm, and throughout my session I aim to stay between 60-70 rpm. By the same token, if I want an easier workout, I may lower the resistance.
4) Now, we're going to add apnea. While still pedaling, we're going to start holding our breath. We're going to pedal the same pace, for the entire session, and we're going to alternate breathing and holding. We want to pick and hold/breathe interval which is challenging, but which we can manage for the entire 15-30 minute session. If we break and spend a couple minutes catching our breath before resuming, we're not getting the full benefit--better to back off on the intensity and maintain the exercise for the full 15-30 minutes.
As for the actual interval, try 25 secs hold, 35 secs breathe (25:35), then repeat. We're going to do this for 15 minutes at least. During the breathing, go ahead and catch your breath, but don't overbreathe or hyperventilate in anticipation for the next hold--that defeats the purpose. As our body warms-up and starts to buffer the CO2 better, we may find that the exercise gets easier. In that case, increase the hold time and reduce the rest time. Maybe we do 5 mins at 25:35, then try 5 mins at 30:30 (that's 30 sec hold, 30 secs breathing), and finally 5 mins at 35:25 (or beyond). I keep everything starting on the minute, it's just easier that way. If we're really feeling ambitious, climb back DOWN the ladder... meaning if we got to 35:25 for five minutes, go straight into 30:30 for five minutes, then 25:35 for five minutes to finish.
And if starting at 30:30 is too much, try 20:40, or even 15:45. If we are challenged and doing the exercise for a solid 15-30 minutes, our breathhold will improve over time.
5) Warmdown. It's particularly important to do a warm down with apnea training because all the protective mechanisms triggered during apnea (particularly bradycardia and vasoconstriction) discourage muscle growth or recovery. So, for warmdown, we do at least 10 minutes of moderate aerobic exercise to get the blood moving back into the muscles. Simplest thing is to keep pedaling the bike (while breathing) for 10 minutes, or move onto your ordinary fitness workout.
Disclaimer: Divers need to be healthy and in good cardiovascular shape to start any dive training program, and have no medical or cardiac conditions that would interfere with freediving. Hypoxic cardio can be very draining, and very challenging. Divers who experience fainting, arrhythmia (irregular heartbeat), dizziness, or racing heartbeat after the exercise should discontinue immediately and consult a doctor; this is NOT normal or common, but I have heard of it happening to recreational spearfishermen who, when they began training more seriously, discovered cardiac conditions which were previously undiagnosed. SoCal Spear-It takes no responsibility for misapplication of this information, or injury or death resulting from its use.