Your back works hard for you. The better you take care of it, the lower your risk for developing back spasms will become. Losing a few pounds if you’re overweight will help relieve the stress on your spine and your joints. Standing up straight and wearing low-heeled shoes will help provide stability and strength in your lower back. Regular physical activity like strengthening exercises for your back and abdomen will also help keep you moving and feeling great. Spending too much time in bed or in a seat will lead to worsening back problems.
Back pain is regularly cited by national governments as having a major impact on productivity , through loss of workers on sick leave . Some national governments, notably Australia and the United Kingdom , have launched campaigns of public health awareness to help combat the problem, for example the Health and Safety Executive 's Better Backs campaign. In the United States lower back pain's economic impact reveals that it is the number one reason for individuals under the age of 45 to limit their activity, second highest complaint seen in physician's offices, fifth most common requirement for hospitalization, and the third leading cause for surgery. [ citation needed ]
I agree with LMTJB. You mentioned weight training. Do you also do crunches? If your abs are tight especially the upper rectus a dominos, and you have a significant release due to massage or stretching in the midback, it could result in a rebound spasm. The imbalance was probably already there and the therapist worked where you wanted the work and the imbalance was increased resulting in spasm. A postural/structural assessment prior to deep work by someone well trained would probably yield a much better outcome. I hope you are feeling better by now.