Finance expert BC Partners has managed to raise £5.4 billion with its latest fund as it attempts to wrest control of Fitness First from shareholders.
The firm's European Capital IX fund had been subjected to unprecedented levels of demand and had long been oversubscribed.
It has resulted in a 60 per cent increase in BC Partners' investor base.
The firm is hoping to raise hundreds of billions of pounds before the end of 2012 and use the capital to consolidate its assets.
BC Partners is concerned that Fitness First could be paralysed by the fact that more than a third of the company is now owned by rival fund Oaktree, entitling the latter firm to block potential covenant wranglings.
If BC Partners fails to service the interest on debts covering Fitness First, lenders could push through an insolvency.
Charlie Bott, managing partner of the firm, said that the deal took longer than usual as arranging finance was much more difficult than during the boom years.