Zimmermann, LPO, Saraste, Royal Festival Hall

If you've just come back from a taxing, tiring orchestral tour, as has the London Philharmonic, the last thing you want to face is a programme of four tough works which demand, at the very least, bright-eyed vigilance but more often a tense, finger-wrecking articulation. So the players must have been relieved to find firm hands on the wheel in the shape of the electrifyingly assured Finnish master Jukka-Pekka Saraste and that most intelligent, repertoire-curious of solo violinists, Frank Peter Zimmermann.

Between them, orchestra and conductor just about pulled off the athletic, if not always the emotional, demands of what is perhaps the 20th century's most rigorous symphonic argument, Nielsen's Fifth. But what tugged discreetly at my tearful depths, at any rate, were the ever-unpredictable emotional landscapes of yet another piece by soulful Czech exile Bohuslav Martinů I've never heard in concert before, the Second Violin Concerto. I know all too well, from speaking to flinty colleagues, that one man's Martinů worship is another man's poison. And, yes, there's often a feeling of "here we go again with those Moravian syncopations" as the composer steps out with another of those poignant 1940s hymns to love and loss from his insecure American haven. Yet the quick departures Martinů takes from familiar paths, the disturbing shifting of harmonic and rhythmic scenes are what make each of the later orchestral works and concertos precious and fresh.

Would the Second Concerto be as engrossing and as profound a journey as each of the instalments in Bĕlohlávek's symphonies cycle earlier this year? I wondered, as an orchestra rather too large for concerto proportions crashed in with instant tragedy. But once Zimmermann (pictured right) had nobly asserted his lonely voice and taken us to places that the full ensemble couldn't reach, the doubts vanished. For me, it's not so much repetition as deep comfort when a famous cadence surfaces again and again. Martinů drew it from his surrealist opera Julietta and seems to have associated it with the great passion of his life, the talented young composer Vítězslava Kaprálová who died so tragically young. But he invariably gives it a different context each time, in this case an essentially tragic one in his big first movement.

Martinů was always a master of the not-quite-slow central movement, here a dream interlude where simple pastoral slips again and again out of focus. How Zimmermann, having passionately projected and clearly etched his earlier part in the argument, must have marvelled at Saraste's iridiscent inscaping of responsive LPO strings before another of Martinů's essential, short cadenzas and a flight into sleep. After that, the finale was all weird trilling and subtle cross rhythms, extrovert but never exactly ordinary. And Zimmermann seemed like an artist soaring free and focused throughout after the pedestrian limitations of the Szymanowski Second Violin Concerto I heard him play in Scotland. I'd rather hear this spirited, chameleonic and implicitly emotional work any day than that or the far more ubiquitous, irredeemably shallow Korngold Concerto.

The Martinů's first-half companion, Beethoven's Egmont Overture, was a terse statement of heroic intent to come, with a depth of sound to the LPO I haven't heard to the same extent in other recent concerts and a surprising sense at the mid-point of a journey that had an almost Sibelian dynamism to it. If the Nielsen needed a second-half preface at all - and it surely didn't - that might best have been the Dane's Helios Overture. Instead we had a strenuously brilliant, heliotropic showpiece by Julian Anderson, The Stations of the Sun, which consumes itself rather early on in its fireballs of sound. It's refreshing to hear a recent piece which begins in focus rather than with the usual wash of percussion, and to go with the flow of bold, exposed melodic lines for the violins. But shape and colour couldn't quite conceal an absence of the first-rate musical thought which would have kept us truly hooked for the work's 18-minute duration.

And as I say, the orchestra shouldn't have been put through that before the mighty Nielsen. But they played both on Saraste's tight rein heroically. The oscillating violas which launch the symphony had none of the usual in-the-beginning mystery, rather a sense of threat from radio-wave interference, soon unleashed. Saraste swept forward, but without haste, in both this disorienting head-on clash and the nobler one of full-hearted hymn versus ad lib side drum - played with more refinement and nuance than usual by the indefatigable Rachel Gledhill. Then, after clarinettist Robert Hill's still small voice of peace, it was on to the leaping sallies and heaven-storming fugues of the ultimate embattled symphonic finale. This was where a bit more time together might have brought a greater depth to the energy, though all credit to brilliant execution throughout. At the end of a volatile, uneasy year, it was apt to go out on a concert which started and ended by celebrating the exhilaration and creativity that can come from conflict.

• Forthcoming LPO concerts listed on the orchestra's website
• See what's on at the Southbank Centre this season
• Find Saraste's Finnish Radio Symphony Orchestra recording of Nielsen's Fourth and Fifth Symphonies on Amazon