Functional impairment in the fast-growing population of the frail elderly is generally acknowledged to be a complex issue in an urgent need of comprehensive addressing. This prompted the authors to focus primarily on seeking out such comprehensively structured interventions that would ideally combine feasibility, ease of application and overall economic viability, all with a view to their prospective wide-scale application, not least in the overstrained public health care sector [34–36].
Indeed, very few studies to date have addressed the combined effects of specifically structured exercise regimens and nutritional supplementation as an effective way of tangibly improving the strength and functionality of the frail elderly individuals, be that nursing home residents or free-living community dwellers, or indeed proposed any practical measures aimed at effectively retarding the age-induced decline in functionality before it slides down into unrecoverable dependency [3, 37, 38].
Since physical frailty is generally construed as a state of reduced physiological reserve associated with an increased susceptibility to disability, whereas physical inactivity and dietary inadequacies are its main contributors , it seemed only prudent to focus the actual investigation primarily on the following key factors as most clearly indicative of the actual nature of this complex problem: mobility, muscle strength and overall nutritional status.
Appreciable improvement of muscle strength in the lower limbs, as gained through progressive resistance training, does not directly translate into effective walking capability. As Skelton et al. observed, isolated improvements of strength and power standardised for body weight may not be sufficient to improve individual functional ability in the elderly people with already impaired functional capabilities . A person may indeed be quick enough to get up from a chair and walk steadily a short distance (e.g. to reach the toilet), but would be quite challenged to venture further away without an assistive device, let alone being able to effectively pursue the activities of daily living without the necessity of contracting outside help.
Rosendahl et al. , even though his study population was recruited from nursing home residents (mean age 84 years; 45 min. exercise sessions pursued 5 times every fortnight over 13 weeks) with severe functional and cognitive impairment, subscribed to the view that overall improvement in physical function, as demonstrated by his study, might well hold substantial potential for being converted into higher activity level or greater self-reliance amongst the frail elderly, consequently enhancing their overall capabilities for more effective pursuit of ADL; this conclusion being fully on a par with our own findings.
Incidentally, Rosendahl did not seem to construe the individual ability to cover longer distance (as routinely assessed by the 6 MW test or other) as a significant marker of individual functional capability, opting for the assessment of the gait speed instead, which in turn seems to undermine to certain extent overall consistency of his approach, especially in view of so much praise having been lavished on the High Intensity Functional Exercise (HIFE) Programme applied throughout his study.
Considering, however, that our own exercise regimen provided for 45 min. uniform exercise sessions 5 times a week, pursued for 7 weeks (the weekend sessions being non-feasible for organisational reasons), we would be somewhat wary of accepting Rosendahl's term HIFE Programme, especially in view that each of his study subjects had his exercises individually tailored by the physiotherapist to suit his individual functional deficits. Arguably, this particular approach seems to make the actual quantification of exercise effectiveness a rather daunting task.
Besides, despite offering rather comprehensive baseline characteristics, Rosendahl neglected to offer, however, any information on whether the application of HIFE Programme actually yielded any quantifiable improvements in terms of downgrading the type of walking aids used by his subjects, which might otherwise be of some value for designing more effectively targeted exercise regimens; this particular type of study generally expected to be intrinsically focused on practical application of its findings.
The results yielded by our own study clearly support the conclusion that only standard exercises in combination with the functionally targeted ones may prove effectively instrumental in appreciably enhancing individual walking capabilities, as assessed by the 6 MW test, despite notably failing to improve overall muscle strength in the knee flexors and extensors. Admittedly, overall muscle strength in the lower limbs is just one of several key factors essentially contributing to the effective performance of independent activities, although its true significance should by no means be underestimated.
Although Bunout et al.  reported that overall walking capabilities in his subjects remained virtually unaffected by resistance training exercises over the 18-month span (i.e. lacked statistical significance), this might reasonably be extrapolated that ca. 50% compliance rate (to which Bunout himself freely admitted) might well be expected to yield closely similar results to 100% compliance rate obtained whilst pursuing standard exercise regimen. Also in assessing the actual walking capabilities of his subjects Bunout for some reason opted for measuring the distance covered over 12 minutes instead of applying the standard 6 MW test, which would certainly have added more credence to his findings. Another intervening factor consisted in the fact that all his subjects were involved in a 15-min. walking period prior to and after the respective resistance training sessions.
It might perhaps also be worth mentioning at this juncture that in ca. 20% of the study subjects who had been allocated progressive resistance exercise regimen a perceptible trend toward diminished reliance on assistive devices was observed (e.g. a walker was replaced with a walking cane by the end of the study), although a study embracing a much longer time span would obviously be required to determine its true, long-term statistical significance. Similar observations were also made by Fiatarone et al.  and Sullivan et al. .
The presently applied resistance exercise regimen was deliberately focused on leg extension, as both the knee and hip extensors are the muscle groups widely acknowledged to be of critical importance in executing such basic postural shifts as sit-to-stand (and vice versa) and walking, with a long-term aim of appreciably enhancing individual functional performance [42, 43].
Fiatarone et al. , who conducted her study on older (mean age 87 years) frail nursing home residents, also reported appreciably improved overall strength in several muscle groups over a 10-week span (45 min. sessions 3 times weekly) in the subjects following intensive resistance exercise programme combined with a nutritional supplementation regimen of a closely similar type.
Bonnefoy et al. , whose randomised study design embraced combined nutritional supplementation and a variety of structured exercises (study population: retirement home residents; mean age over 83 years; 60 min. exercise sessions pursued 3 times weekly over 9 months), concluded that such a combined intervention strategy in the frail elderly was indeed a feasible therapeutic modality (ca. 50 – 60% success rate), even though he conspicuously failed to elucidate the actual nature of the control activity (memory), as well as his study protocol did not provide for any clear-cut discrimination in terms of the actual duration of the respective types of exercises (e.g. no juxtaposition between the progressive resistance type and the other exercises) that would reasonably merit some quantification, with a view to establishing their respective impact on the outcomes under study.
The study pursued by Bunout et al. , embracing the free-living 70-year olds, was altogether different in its design, though, as it spanned 18 months worth of follow-up during which his subjects were assessed four times, although compliance rates with respect to both their attendance at the resistance training sessions (1 h sessions twice weekly) and nutritional supplementation were relatively low (56% and 48%, respectively), giving therefore some grounds to doubt the actual effectiveness of both regimens.
Since the composition of the nutritional supplement used by Bunout was on a par with the one offered to our own study subjects (NUTRIDRINK®), overall effectiveness of the applied supplementation regimen should be assessed in terms of the respective compliance rates. The fact that Bunout had his nutritional supplement diluted in a soup or porridge seems to have significantly contributed to a relatively low compliance rate.
The authors fully appreciate the concerns voiced by Paul L. de Vreede , though, who pointed out that muscle strength gain induced by resistance exercise regimen is invariably lost after a relatively short detraining period (i.e. when a regular pursuit of resistance exercise regimen is discontinued), whereupon the body readily adjusts to the diminished physiological demand and consequently all the beneficial adaptations achieved throughout the exercise period may in fact be lost.
Those vital concerns actually prompted the authors to discuss the issue of detraining in some detail with the study subjects, ostensibly in an attempt to encourage them to continue the regimens on their own accord, once the study has been concluded. As it happened, most of them actually proved quite enthusiastic about performing the various exercises and seemed to understand well enough that a consistent and diligent pursuit of the prescribed regimens well beyond the actual time frame of the study was actually supposed to help them sustain the already restored capabilities, which they unequivocally regarded as a tangible, long-term benefit. Even though the present study design did not expressly provide for any follow-up and no data are therefore available to substantiate the authors' claim, they do have good reasons to believe that with regard to a number of former study subjects the obvious benefits of continuation proved a persuasive enough argument.
In his study De Vreede demonstrated the superiority of functional-task exercises over the resistance type in terms of the results of the former standing to be preserved for much longer. His findings are in fact very much on a par with the results of our own investigation, where the multi-sensory exercises, the core component of FOE, were found to demonstrate by far the greatest potential with regard to enhancing individual functional capabilities, as they effectively stimulate individual balance, overall movement co-ordination and reaction time in responding to situations of impending postural risk, e.g. incidental fall, as well as prepare a person much better to cope effectively afterwards. Skelton et al. seems to share this view and even ventures to say that enhanced individual functional capabilities specifically contribute to tangible improvement in overall quality of life for older people .
Although the therapeutic value of SE should on no account be underestimated, as they effectively prevent muscle cramps, enhance the range of joint movement and generally improve peripheral circulation, this particular type of exercises may never suffice as a self-contained therapeutic option in addressing the complex issue of impaired functional capabilities.
Even though the authors strongly believe that for best therapeutic results both regimens (SE + FOE) should always be pursued in combination, it is actually the FOE type that can safely be recommended to a much more diversified population of frail elderly (inclusive of those suffering from a diversity of neurological and cardio-vascular disorders, as well as those remaining in post-operative recuperation), irrespective of their specific social setting, as they have positive impact over a significantly larger number of bodily systems and functions.
In seeking to design optimum exercise interventions programme de Vreede advocated that specifically targeted, functional-task exercises be primarily considered in view of their substantial potential for long-term effectiveness. The authors fully support this view in so far as more in-depth research is still required in order to determine beyond reasonable doubt which specific exercise interventions of the FOE type hold by far the greatest potential to yield the most promising, long-term results and should therefore primarily be considered as the core element of any viable physical rehabilitation programme under development; overall validity and persuasive character of de Vreede's findings notwithstanding .
Admittedly, overall complexity of the issue addressed by the present study clearly merits pursuit of further studies of a closely similar, multi-factorial intervention design, though preferably conducted over much longer time span, as well as best targeting the over 60s as the population standing by far the best chance of a successful outcome, in order to verify whether the present findings, clearly encouraging as they appear, might actually have sufficient potential to develop into a trend of indisputable clinical significance, especially in terms of possible application in a comprehensively designed, nationwide programme specifically aimed at addressing the problem of a steadily growing proportion of the frail seniors dependent for their activities of daily living.