When you increase your strength training, you have more demands on recovery. Recovery includes the following:
- Sleep (Number 1 recovery tool)
- Nutrition (Number 2 recovery tool)
- Myofacial release/stretching
- Light movement to get blood flowing
Since you are saying that you are still fatigued after you get 8 hours of sleep, there are a few possibilities:
- The sleep is not restful. It could be the fatigue preventing a good restful sleep, or other outside stress factors.
- You need to change your nutrition. With increased demands on your body come increased demands for the raw materials (i.e. food) to rebuild your muscle into a stronger self. You might need to increase your food, or at least certain portions of it. If you aren't taking a multivitamin, it might be worth starting.
- You might need to change your approach to training. If the training is pushing your further and further into a fatigue deficit, you need to build in some recovery options.
- Do a cool down after training. 5 minutes of walking at a light pace to bring down your heart rate and keep blood flowing with more oxygen can help clear out some of that fatigue.
In all likelihood you have more than one of these things at work at the same time. 8 hours of sleep is a good starting point. You also may want to increase the food a little--just be careful to make small changes at a time here. In all likelihood you'll need three types of training days:
- Volume: this is where you use moderate weight (75-85%) for longer sets. 3-5 sets of 6-15 reps.
- Speed: this is where you use light weight (60-70%) for a number of short sets trying to keep the speed of your movement as fast as possible.
- Heavy: this is where you lift in the 90% range for 3-4 sets of 2-3 reps.
The volume day will be the toughest to recover from, but it's where you really build a foundation of strength. The speed work is an active recovery day, so you'll do as many sets of 2-3 reps as you can while keeping the bar speed the same. As soon as the bar speed slows down you stop. The heavy day is where you get to to test out your strength a bit, and get used to heavier weights.
This general approach helps you recover better from your exercise over time and really helps you progress in strength at a steady pace. If you stagger the work so that you have three main exercises, in any one week your volume, speed, and heavy days are on the different main exercises.