I'm a big believer in German Volume Training for either, a) rapid increase muscle strength and mass, or b) shocking lagging bodyparts into growth. The difference between the two is real simple: For athletes in between competitions (such as Spring and Fall) GVT is a great way to gain muscle in a short or condensed amount of time. For athletes that have found themselves doing the same routine for months without getting any noticeable growth or increases in strength, GVT is a superior form of 'shock therapy' that will 'motivate' your body into growth.

History (from http://www.charlespoliquin.com): This training system originated in Germany in the mid-’70s and was popularized by Rolf Feser, who was then the National Coach of Weightlifting.

A similar protocol was promoted by Vince Gironda (pictured left) in the US. In Germany, the 10 sets method was used in the off-season to help weightlifters gain lean body mass. It was so efficient that lifters routinely moved up a full weight class within 12 weeks. German Volume Training was the base program of Canadian weightlifter Jacques Demers, a silver medalist in the Los Angeles Olympic Games who was coached by Pierre Roy. Jacques was known in weightlifting circles for his massive thighs, and he gives credit to the German method for achieving such a spectacular level of hypertrophy. The same method was also used by Bev Francis in her early days of bodybuilding to pack on muscle.

The German Volume Training program works because it targets a group of motor units, exposing them to an extensive volume of repeated efforts, specifically 10 sets of a single exercise. The body adapts to the extraordinary stress by hypertrophying the targeted fibers. To say this program adds muscle fast is probably an understatement. Gains of 10 pounds or more in six weeks are not uncommon, even in experienced lifters!

There's a few things you need to be aware of before starting German Volume Training:

Only perform GVT on the 20% of exercises that drive 80% of the results: Flat Benchpress, Squat, Seated Shoulder Press (front), Bar/DB Row, laying Hamstring Curls.

Because GVT is high volume, YOU NEED to avoid any exercises that can cause injury such as tendinitis, joint pain, etc.

Because GVT is high volume, YOU DO NOT need to do a million different exercises in the same workout.

Because GVT is high volume, YOU NEED to plan your workouts and exercise splits so that you're not over-taxing bodyparts...
...For example, you do GVT for Bent Rows on Monday....you DO NOT need to do Deadlifts on Tuesday. 

You NEED NEED NEED to know your baseline weight for the GVT exercises you're going to do. Without getting your baseline, you won't know your progress (not being able to measure progress = wasting time). For example, you're going to do weeks of GVT on Flat Bench. Know your heaviest weight for 8 reps on Flat Bench before you start GVT. At the end of your GVT period, do Flat Bench for normal sets and reps and measure your average weight for 8 reps. You should see noticeable increases from your baseline: this is called "benchmarking your progress."

German Volume Training should kick your ass - if you think it's easy, you're doing it wrong. 

How to approach German Volume Training:
  • Set your number of weeks you plan to do GVT; set a macro-goal of doing it consistently for x weeks. In week 1, set a micro-goal for next week. This will be real easy to understand, you will know if you coulda gone heavier.
  • Set threshold rules, mine are:
    • If I can't do 10 reps on sets 1-5, lower the weight. 
    • If I can do 12 reps on sets 5-8, increase the weight for sets 9&10. 
    • If I can't do the 10th rep on sets 5-8, add 15 seconds rest. 
    • Add two sets of 15 as "bonus sets" if I don't feel like I got my ass kicked. 
Make a commitment - you can't just "try GVT" and see results - you need to commit to it; I suggest a minimum of 4 week cycles.

Create your program: 
GVT is a tool, you can choose how to use the tool. Personally, I've done every form of GVT program I've seen published. However, my latest approach is to do GVT on lagging bodyparts (the bodyparts I want to see improvement for my next show) once per week. 

My program is one day of GVT per week. I do one upperbody bodypart for 10X10, then another smaller part for 5X10 (the same for lowerbody). I keep all sets at 1m rest - I bring a stopwatch with me.

German Volume Training Overview:
One Exercise. Stick with heavier, compound-style lifts that tax major muscle groups.
  1. For each exercise, you will be performing 10 sets of 10 reps. 
  2. Start with 50 to 60% of your one rep max for that lift. 
  3. Perform as many reps as possible for each of the 10 sets. 
  4. There is no need to get each set to failure. Get close to failure - the overall volume is your goal. 
  5. When you can perform 100 total reps, or 10 sets of 10 reps, add 5 pounds to the bar in the next GVT session. 
Rest Pause. You will be resting approximately 60-90 second between sets. There are numerous forms of GVT floating around the Internet, some a variation of Vince Gironda’s 8x8 training, and some with incredibly short rest periods. Resist the urge to lower your rest periods under the 60 second mark. Limiting rest like this will force you to decrease the load. You’re already working with weights slightly above half of your 1RM. It does you no good to use lighter weights then this. For most exercises, a 60 second rest works best. 

Pro tip - German Volume Training as a form of cardio:

Because GVT is predicated on 1m rest periods between 10 rep sets, you can use this program as a form of cardio. What form of cardio is based on 1 min intervals with 20+ second bursts? High Intensity Interval Training (HIIT). 10 reps of an exercise at correct tempo should yield 20 seconds to 25+ seconds of time.

So, by doing GVT with the correct lifting tempo you are essentially mimicking HITT. Which, if you had to choose between a cardio session that builds cardiovascular strength and a cardio session that builds muscular strength, which would you choose? GVT!

Additional links (references):
http://www.simplyshredded.com/german-volume-training-a-new-look-at-an-old-way-to-build-mass-strength.html
http://www.charlespoliquin.com/ArticlesMultimedia/Articles/Article/261/A_Look_Back_and_Ahead_at_German_Volume_Training.aspx
http://muscleandbrawn.com/german-volume-training/