Weight lifting and tai chi

In about 1985 I was working out at a Nautilus facility and that's where I met my first tai chi instructor, Bill Grizzle. He studied under Wai-Sun Liao in Chicago. I was wearing an Ed Parker's Studios T-shirt and that started the conversation. Knowing that weights and tai chi were thought to be mutually exclusive by many tai chi people I asked what his teacher would think of him weight-training he said "He'd freak out".
Marc Rowe sent this along on the subject. It's from a website by Fernando Bernall.

 The Fitness Professional: A Model in the Health care Field, Part I

Squats and Deadlifts: add-ons for Tai Chi
September 17th, 2009

Squats and deadlifts are considered closed kinetic chain (CKC) exercises. Meaning, that the force to overcome the load (barbell), is applied to an unmovable object (the ground) and not to the object being lifted. Open kinetic chain (OKC) exercises differ in that the force applied, moves the load, like in a bench press or bicep curl. In the following article, I will share some thoughts on the common ground these exercises share with tai chi and how, by applying principles of strength training, the tai chi practitioner can develop more functional strength and endurance.
The reader should know that I am fully aware of the negative views held within some Tai Chi circles regarding weight training. It is considered detrimental by many who think that weight lifting distracts from Tai Chi’s internal development and that too much emphasis is placed on muscular strength at the expense of softness and flow.
While I do think that everyone should practice some form of weight training, in particular dead lifts and squats, and seek to increase muscle mass, my intention is to show how principles of resistance training used within weight lifting, can and should be applied to Tai Chi practice. I’ll add that this is a necessity to Tai Chi practitioners who live in the West whose lifestyle is nowhere as physically demanding as that of our Tai Chi forefathers.
The process through which leg strength is gained through squats or dead lifts, is applicable to tai chi practice and several principles of strength and endurance training need to be understood.
GPO: Gradual Progressive Overload
If I’m squatting 3 sets of say 200 lbs. of 15 reps each twice per week, it won’t be long before adaptation takes place. This falls in line with the SAID (Specific Adaptation to Imposed Demand) principle. Meaning, that my legs and back will only get as strong (adapt), as they need to be in order to accommodate the 200 lbs of weight (demand). If I want to improve in strength, I need to increase the weight or do more reps to improve in muscular endurance in a GPO fashion.
The same can be said for Tai Chi practice. If the practitioner wants to increase leg strength, then he or she needs to increase the load. However, in contrast to squats or dead lifts (which cover a wider range of motion from the legs being bent to around a 90 degree angle, as in squats, to full extension, and are isotonic in nature), much Tai Chi practice is limited to a given depth of stance through most of form practice. The limited range almost categorizes Tai Chi practice as isometric in nature. This means that the legs are only strong withing a given range of motion.. And, while in the Tai Chi form are some postures that require deeper lowering of the body, these are few and far in between; Snake Creeps Down, comes to mind..
Furthermore, even if the practitioner practiced Tai Chi standing at various depths in order to increase intensity, he is limited by his own weight. Thus, in order to improve in strength through Tai Chi practice, there needs to be change in the daily routine and such change can be accomplished through what is known as FITT (Frequency, Intensity, Time, and Type)..
Frequency:
Have we not all heard of practitioners of old practicing their form several times per day? A dozen times and even more on daily basis? Sure we have. Yet, in today’s fast pace lifestyle, many find it difficult to allot sufficient practice time daily. Lamentable, in my opinion, is the creation of short forms which were choreographed for those too busy to practice.
Intensity:
In exercise, intensity is often determined or aimed to, by a percentage of maximum heart rate (MHR) or by a percentage of one rep maximum (1RM). While these parameters are outside of Tai Chi practice, there needs to be method through which intensity can be gauged, even if it is perceived rate of exertion, (PRE). Otherwise, how can one know if improvement is taking place? How is “effort” quantified?
Time:
Here we need to really take an honest look at our practice. We know that shorter forms have been developed to accommodate those whose time limitations prohibits any extended practice time.. But without an appropriate amount of time during one’s practice, how can physiological improvements take place?
We know that it takes at least 15 to 20 minutes of constant exercise before the body enters in the the so called “fat burning zone” How can a 15 minute form bring into play the energy systems involved in weight management? It can’t. If one is to reap any benefit from Tai Chi practice, one should at least commit to 30 minutes or more of daily practice.
Holding postures for a given amount of time and gradually increasing it will also fall under the “Time” aspect of FITT.
Type:
Type can fall into the resistance or cardiovascular approach to form practice. For example, sometimes I like to practice wearing a weighted vest. By adding the weight, my body is challenged from a resistance perspective. Practicing the form at a faster pace presents a cardiovascular component.

Any change on one or more of the FITT items on our Tai Chi practice would change the GPO and thus improve the practice martially and health wise..