For many people the time you have in your week for BJJ training is precious. Time spent on the mat learning technique and sparring is generally accepted as the fastest way to improve. However, strength and conditioning is an important aspect of BJJ and your game would most likely benefit from it.
However finding the time to go to the gym a couple times of week in addition to regular BJJ practice is tough. This leaves us with the question: will your overall game benefit from swapping one day for strength and conditioning or are you better off spending as much time as possible on the mat developing technique and improving through sparring?
This is a tough one and there is no correct answer. The amount of gym work required versus time on mats really depends on your situation and what your goals are.
How much if any?
Obviously not everyone needs to be in the gym lifting weights every week. Any BJJ practitioner under the age of 16 should be spending 100% of their training time on the mats. Likewise, a BJJ hobbyist who trains max twice a week for fitness will get little benefit if any by swapping BJJ practice for specific conditioning training.
Some people may be able to incorporate the fitness and strength training into their normal BJJ practice session. Some schools have circuit classes and exercise machines that can be used as part of a warm-up or might even a conditioning class listed on the timetable.
Injury Rehab & Prevention
Lots of BJJ athletes train with injuries that require constant management. For example many people need to undertake specific strength training to mitigate against back pain. This specific training is often key to ensuring that they are not forced off the mats for extended periods. Injury recovery programs typically call out for muscle specific training that can either be done in the gym or sometimes at home.
Strength training is also a key part of injury prevention. By proactively working on areas of weakness and tightness in your body you can reduce the risk of injuries and niggles that could keep you off the mat. Many BJJ practitioners also incorporate yoga/Pilates into their schedule for the same reason.
For example there is strong evidence that glut stability and strength decrease the risk of ankle injuries and sprains. In order to protect myself from sustaining another bad ankle sprain I try to work on glut strengthening at least once a week as part of my Strength and conditioning plan. Having a proactive approach to injury prevention ensures that I spend the maximum amount of time possible on the mats during the year.
If you are training for a competition or compete regularly you will know that extra strength and conditioning training will improve your chances of success. BJJ training and sparring will help somewhat to maintain your levels of cardio and strength but in order to make further gains you will need to add extra non BJJ sessions strength and condition sessions to your schedule.
Almost all of the top BJJ competitors have strength and conditioning program that is incorporated into their overall training schedule. In recent years we have seem a massive rise the level of conditioning and athleticism that is required to win at the top level. Athletes such as Gordon Ryan, Andre Galvao, and Rodolfo Vieira have proven this through the success that they have had.
Even at Masters level BJJ competition the level of athleticism has risen dramatically in recent years as people have better information and supplements to help them optimize their training. When two athletes of similar skill and size face off it is often the superior strength and conditioning of one athlete that ultimately decides the bout.